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A comprehensive review of ZnO materials and devices
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10.1063/1.1992666
/content/aip/journal/jap/98/4/10.1063/1.1992666
http://aip.metastore.ingenta.com/content/aip/journal/jap/98/4/10.1063/1.1992666

Figures

Image of FIG. 1.
FIG. 1.

Stick and ball representation of ZnO crystal structures: (a) cubic rocksalt , (b) cubic zinc blende , and (c) hexagonal wurtzite . The shaded gray and black spheres denote Zn and O atoms, respectively.

Image of FIG. 2.
FIG. 2.

Total energy vs volume (both per ZnO f.u.) for the three phases: zinc blende (squares), wurtzite (diamonds), and rocksalt (circles). The zero of energy is the sum of the total energy of an isolated Zn and an isolated O atom. [Reprinted with permission from J. E. Jaffe and A. C. Hess, Phys. Rev. B 48, 7903 (1993). Copyright 1993 by the American Physical Society.]

Image of FIG. 3.
FIG. 3.

Schematic representation of a wurtzitic ZnO structure having lattice constants in the basal plane and in the basal direction; parameter is expressed as the bond length or the nearest-neighbor distance divided by (0.375 in ideal crystal), and and (109.47° in ideal crystal) are the bond angles.

Image of FIG. 4.
FIG. 4.

Lattice-plane spacings as functions of pressure for the ZnO phase. The crosses denote increasing pressure and the circles decreasing pressure. Miller indices are indicated for each set of data. [Reprinted with permission from J. M. Recio, M. A. Blanco, V. Luaña, R. Pandey, L. Gerward, and J. Staun Olsen, Phys. Rev. B 58, 8949 (1998). Copyright 1998 by the American Physical Society.]

Image of FIG. 5.
FIG. 5.

Examples of EDXD spectra indicating the coexistence of the wurtzite and rocksalt phases around (increasing pressure) and the emergence of the wurtzite phase at upon decompression. The spectra are presented in cascade for clarity. The labels W and RS refer to wurtzite and rocksalt, respectively. The x-ray-diffraction lines from the Cu pressure gauge and the gasket material are labeled as Cu and g, respectively. [Reprinted with permission from S. Desgreniers, Phys. Rev. B 58, 14102 (1998). Copyright 1998 by the American Physical Society.]

Image of FIG. 6.
FIG. 6.

(a) Normal-emission spectra for photon energies ranging from . The spectra were normalized with respect to the photon flux. (b) The bulk-band structure of ZnO, corresponding to . [Reprinted from R. T. Girard, O. Tjernberg, G. Chiaia, S. Söderholm, U. O. Karlsson, C. Wigren, H. Nylèn, and I. Lindau, Surf. Sci. 373, 409 (1997), Copyright 1997, with permission from Elsevier.] The dashed lines are the LDA calculation results reproduced from Schröer et al. (Ref. 86).

Image of FIG. 7.
FIG. 7.

(a) Off-normal-emission spectra of the clean surface recorded at and along the direction and at and along the [0001] direction. The incidence plane of the light was parallel to the direction for both detection directions. The spectra are shown with 2° interval. The peak positions, indicated by the vertical bars, were determined from the second derivative of the spectra. The position of the valence-band maximum was determined from the normal-emission spectrum taken at by extrapolating the onset of the valence-band emission as shown in the inset of the right panel. (b) The measured dispersion of the O dangling-bond state (open circles) and the bulk-band-related states (filled circles) along the and axes. The hatched area corresponds to the projected bulk-band region and the bold dashed line indicates the O dangling-bond bands, both of which have been calculated using the model by Wang and Duke (Ref. 93). The thin dashed lines which are located above the projected bulk bands are the dangling-bond bands obtained from the LDA calculations. [Reprinted with permission from K. Ozawa, K. Sawada, Y. Shirotori, K. Edamoto, and M. Nakatake, Phys. Rev. B 68, 125417 (2003). Copyright 2003 by the American Physical Society.]

Image of FIG. 8.
FIG. 8.

(a) LDA bulk-band structure of ZnO as calculated using a standard pseudopotential (PP) (left panel) and using SIC-PP (right panel). The horizontal dashed lines indicate the measured gap energy and -band width. (b) Comparison of the calculated and measured valence bands of ZnO. The left panel shows the standard LDA, while the right panel shows the SIC-PP results. [Reprinted with permission from D. Vogel, P. Krüger, and J. Pollmann, Phys. Rev. B 52, R14316 (1995). Copyright 1995 by the American Physical Society.]

Image of FIG. 9.
FIG. 9.

Band structures for ZnO: (a) structure at , (b) structure at , and (c) structure at . [Reprinted with permission from J. E. Jaffe, J. A. Snyder, Z. Lin, and A. C. Hess, Phys. Rev. B 62, 1660 (2000). Copyright 2000 by the American Physical Society.]

Image of FIG. 10.
FIG. 10.

Total density of states (DOS) for ZnO in the (a) structure at and , structure at , and (b) and structures at . [Reprinted with permission from J. E. Jaffe, J. A. Snyder, Z. Lin, and A. C. Hess, Phys. Rev. B 62, 1660 (2000). Copyright 2000 by the American Physical Society].

Image of FIG. 11.
FIG. 11.

Elastic moduli of ZnO vs pressure at ambient temperature. The slope of the and pressure dependences is positive ( and ), whereas that for and is negative ( and . [Reprinted with permission from F. Decremps, J. Zhang, B. Li, and R. C. Liebermann, Phys. Rev. B 63, 224105 (2001). Copyright 2001 by the American Physical Society.]

Image of FIG. 12.
FIG. 12.

Dependence of piezoelectric constants and of ZnO on temperature [(a) and (b)] and stress [(c) and (d)], respectively. used by Hill and Waghmare correspond to used here. [Reprinted with permission from N. A. Hill and U. Waghmare, Phys. Rev. B 62, 8802 (2000). Copyright 2000 by the American Physical Society.]

Image of FIG. 13.
FIG. 13.

(a) Raman spectra of the bulk ZnO sample. The first-order phonon modes of ZnO are indicated by the vertical solid lines. The vertical dashed-dotted lines mark the features due to multiple-phonon-scattering processes. (b) Raman spectra for the thin-film ZnO sample. The vertical dotted lines indicate the Raman-active sapphire substrate phonon mode frequencies. [Reprinted with permission from N. Ashkenov et al., J. Appl. Phys. 93, 126 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 14.
FIG. 14.

Top: pressure dependence of the observed optical phonons. Open (full) symbols: propagation of light perpendicular (parallel) to . Bottom: phonon mode splitting vs pressure. The solid lines are the linear least-squares fits to the experimental points. [Reprinted with permission from F. Decremps, J. Pellicer-Porres, A. Marco Saitta, J.-C. Chervin, and A. Polian, Phys. Rev. B 65, 092101 (2002). Copyright 2002 by the American Physical Society.]

Image of FIG. 15.
FIG. 15.

Raman-backscattering spectrum of as-grown single-crystal ZnO after background subtraction. The sample was irradiated with the line of an Ar laser and a power of . The solid line represents a least-squares fit of six Gaussian lines to the data. The dashed lines indicate the individual local vibrational modes. The peak positions are indicated in the plot. [Reprinted with permission from N. H. Nickel and K. Fleischer, Phys. Rev. Lett. 90, 197402 (2003). Copyright 2003 by the American Physical Society.]

Image of FIG. 16.
FIG. 16.

Wurtzite ZnO lattice parameters as a function of temperature. [Reprinted with permission from R. R. Reeber, J. Appl. Phys. 41, 5063 (1970). Copyright 1970, American Institute of Physics.]

Image of FIG. 17.
FIG. 17.

Thermal conductivity of nanometer, submicrometer, and micrometer particle size ZnO heated from room temperature to at . [Reprinted with permission from T. Olorunyolemi, A. Birnboim, Y. Carmel, O. C. Wilson, Jr., and I. K. Lloyd, J. Am. Ceram. Soc. 85, 1249 (2002). Copyright 2002, Blackwell Publishing.]

Image of FIG. 18.
FIG. 18.

Thermal conductivity of fully sintered ZnO heated from room temperature to . [Reprinted with permission from T. Olorunyolemi, A. Birnboim, Y. Carmel, O. C. Wilson, Jr., and I. K. Lloyd, J. Am. Ceram. Soc. 85, 1249 (2002). Copyright 2002, Blackwell Publishing.]

Image of FIG. 19.
FIG. 19.

The thermal conductivities of ZnO (엯), (●), and for (▵) and 0.1 (◻) as a function of inverse temperature. [Reproduced by permission of the Royal Society of Chemistry from T. Tsubota, M. Ohtaki, K. Eguchi, and H. Arai, J. Mater. Chem. 8, 409 (1998).]

Image of FIG. 20.
FIG. 20.

Specific-heat data measured for pure ZnO compared to the data for varistor ZnO. [Reprinted with permission from W. N. Lawless and T. K. Gupta, J. Appl. Phys. 60, 607 (1986). Copyright 1986, American Institute of Physics.]

Image of FIG. 21.
FIG. 21.

Fit to the pure ZnO data (a) using the Schottky model (this fit yields a Debye temperature of ) and (b) using the Einstein model. is obtained by removing the Debye and Schottky contributions. The Einstein oscillators are identified as the Zn interstitials. [Reprinted with permission from W. N. Lawless and T. K. Gupta, J. Appl. Phys. 60, 607 (1986). Copyright 1986, American Institute of Physics.]

Image of FIG. 22.
FIG. 22.

Experimental (circles) and theoretical (solid line) Hall mobilities as a function of temperature in bulk ZnO. [Reprinted from D. C. Look, D. C. Reynolds, J. R. Sizelove, R. L. Jones, C. W. Litton, G. Cantwell, and W. C. Harsch, Solid State Commun. 105, 399 (1998), Copyright 1998, with permission from Elsevier.]

Image of FIG. 23.
FIG. 23.

Experimental carrier concentration (triangles) corrected for Hall factor and theoretical fit (solid line) as a function of inverse temperature for bulk ZnO. [Reprinted from D. C. Look, D. C. Reynolds, J. R. Sizelove, R. L. Jones, C. W. Litton, G. Cantwell, and W. C. Harsch, Solid State Commun. 105, 399 (1998), Copyright 1998, with permission from Elsevier.]

Image of FIG. 24.
FIG. 24.

Temperature dependence of the mobility of the heterostructure (squares) and the -thick ZnO single-layer (triangles) control sample. [Reprinted with permission from T. Edahiro, N. Fujimura, and T. Ito, J. Appl. Phys. 93, 7673 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 25.
FIG. 25.

Comparison of the calculated electron drift velocity vs electric field for the wurtzite-structure ZnO (solid) and GaN (dashed) at . [Reprinted with permission from J. D. Albrecht, P. P. Ruden, S. Limpijumnong, W. R. L. Lambrecht, and K. F. Brennan, J. Appl. Phys. 86, 6864 (1999). Copyright 1999, American Institute of Physics.]

Image of FIG. 26.
FIG. 26.

Schematic drawing of a hydrothermal growth system. [Reprinted from T. Sekiguchi, K. Obara, T. Shishido, and N. Sakagami, J. Cryst. Growth 214/215, 72 (2000), Copyright 2000, with permission from Elsevier.]

Image of FIG. 27.
FIG. 27.

Schematic sketch of the ZnO crystal melt growth apparatus [after Nause et al. (Ref. 175)].

Image of FIG. 28.
FIG. 28.

Schematic diagram showing the epitaxial relationships of ZnO (0001) grown on (0001).

Image of FIG. 29.
FIG. 29.

SEM images of faceting ZnO films grown on bulk ZnO substrates (a) on surface and (b) on surface. [Reprinted from K. Sakurai, M. Kanehiro, T. Tanabe. S. Fujita, and S. Fujita, J. Cryst. Growth 209, 522 (2000), Copyright 2000, with permission from Elsevier.]

Image of FIG. 30.
FIG. 30.

The FWHM variation of the XRD -rocking curve of the ZnO film grown on the (0001) sapphire substrate at 550 and . [Reprinted with permission from K.-K. Kim, J.-H. Song, H.-J. Jung, W.-K Choi, S.-J. Park, and J.-H. Song, J. Appl. Phys. 87, 3573 (2000). Copyright 2000 American Institute of Physics.]

Image of FIG. 31.
FIG. 31.

Optical emission spectra of the oxygen plasma.

Image of FIG. 32.
FIG. 32.

Schematic diagram of the atom positions for basal ZnO grown on -plane sapphire. The dots mark the O-atom positions and the dashed lines show the sapphire -plane unit cells. The open squares mark the Zn-atom positions and the solid lines show the ZnO basal-plane unit cell.

Image of FIG. 33.
FIG. 33.

Stereographic projections of the x-ray pole figure results for the ZnO reflection for a ZnO film grown on (a) (inset) a -plane sapphire substrate and (b) an -plane sapphire substrate. The in-plane orientation of sapphire is indicated by a sapphire measurement (filled circles). [Reprinted with permission from P. Fons, K. Iwata, A. Yamada, K. Matsubara, S. Niki, K. Nakahara, T. Tanabe, and H. Takasu, Appl. Phys. Lett. 77, 1801 (2000). Copyright 2000 American Institute of Physics.]

Image of FIG. 34.
FIG. 34.

AFM surface observation with a contact mode. (a) H-pretreated sample (grain size of ) and (b) O-pretreated sample (grain size of ). [Reprinted with permission from M. Sano, K. Miyamoto, H. Kato, and T. Yao, Jpn. J. Appl. Phys., Part 2 42, L1050 (2003). Copyright 2003, Institute of Pure and Applied Physics.]

Image of FIG. 35.
FIG. 35.

(a) RHEED pattern taken along the direction of ZnO after of growth. [Reprinted from P. Fons, K. Iwata, S. Niki, A. Yamada, and K. Matsubara, J. Cryst. Growth 201–202, 627 (1999), Copyright 1999, with permission from Elsevier.] (b) RHEED patterns along ZnO and ZnO after deposition of about . [Reprinted with permission from P. Y. Chen, D. M. Bagnall, H.-J. Koh, K.-T. Park, K. Hiraga, Z.-Q. Zhu, and T. Yao, J. Appl. Phys. 84, 3912 (1998), Copyright 1998, American Institute of Physics.]

Image of FIG. 36.
FIG. 36.

RHEED patterns show the surface morphology evolution during initial growth stages. (a) The (0001) surface after oxygen plasma treatment. The MgO buffer layer (b) before and (c) after 2D-3D transition. The LT-grown ZnO layer on MgO buffer (d) before and (e) after annealing; (f) the ZnO epilayer after a few minutes of growth on the buffer layer. [Reprinted with permission from Y. Chen, H.-J. Koh, S.-K. Hong, and T. Yao, Appl. Phys. Lett. 76, 559 (2000). Copyright 2000, American Institute of Physics.]

Image of FIG. 37.
FIG. 37.

Growth rate of ZnO layers against Zn beam flux. [Reprinted with permission from H. Kato, M. Sano, K. Miyamoto, and T. Yao, Jpn. J. Appl. Phys., Part 1 42, 2241 (2003). Copyright 2003, Institute of Pure and Applied Physics.]

Image of FIG. 38.
FIG. 38.

Polar-angle-dependent CAICISS spectra from ZnO films with (a) Zn preexposure and (b) O-plasma preexposure. The solid squares and open circles indicate the experimental and simulated spectra [Zn polar for (a) and O polar for (b)], respectively. The spectra are plotted as a function of an incident angle, where 90° minus a polar angle is an incident angle. [Reprinted with permission from S. K. Hong, T. Hanada, H. J. Ko, Y. Chen, T. Yao, D. Imai, K. Araki, M. Shinohara, K. Saitoh, and M. Terauchi, Phys. Rev. B 65, 115331 (2002). Copyright 2002 by the American Physical Society.]

Image of FIG. 39.
FIG. 39.

RHEED pattern of ZnO layer along the direction (a) at the end of growth and at a substrate temperature of and (b) after cooling down to .

Image of FIG. 40.
FIG. 40.

Schematic diagram of a pulsed-laser-deposition system [after Singh et al. (Ref. 244)].

Image of FIG. 41.
FIG. 41.

AFM images of the ZnO films grown at various oxygen pressures: (a) , (b) , (c) , and (d) , with a nucleation layer of grown at . [Reprinted with permission from S. Choopun, R. D. Vispute, W. Noch, A. Balsamo, R. P. Sharma, T. Venkatesan, A. Iliadis, and D. C. Look, Appl. Phys. lett. 75, 3947 (1999). Copyright 1999, American Institute of Physics.]

Image of FIG. 42.
FIG. 42.

Hall mobility and carrier concentration vs oxygen pressure for ZnO growth. For comparison, the data for the ZnO film grown at with the nucleation layer grown at are also shown. [Reprinted with permission from S. Choopun, R. D. Vispute, W. Noch, A. Balsamo, R. P. Sharma, T. Venkatesan, A. Iliadis, and D. C. Look, Appl. Phys. Lett. 75, 3947 (1999). Copyright 1999, American Institute of Physics.]

Image of FIG. 43.
FIG. 43.

XRD pattern of a ZnO thin film deposited under optimized conditions. The rocking curve recorded for the (002) line is shown in the inset. [Reprinted with permission from V. Craciun, J. G. E. Gardeniers, and I. W. Boyd, Appl. Phys. Lett. 65, 2963 (1994). Copyright 1994, American Institute of Physics.]

Image of FIG. 44.
FIG. 44.

Temperature dependence of the ZnO growth rate using isopropanol (black rectangles) or tertiary butanol (black circles) as the oxygen precursor. The DEZn flow rate is . The reactor pressure for both sets of samples is . [Reprinted from C. Kirchner, T. Gruber, F. Reuss, K. Thonke, A. Waag, C. Giessen, and M. Heuken, J. Cryst. Growth 248, 20 (2003), Copyright 2003, with permission from Elsevier.]

Image of FIG. 45.
FIG. 45.

CL linewidth of the ZnO near band-edge emission as a function of LT buffer layer thickness and growth temperature. The linewidth decreases with increasing growth temperature and with increasing layer thickness of the LT ZnO buffer. [Reprinted from A. Dadgar, N. Oleynik, D. Forster, S. Deiter, H. Witek, J. Blasing, F. Bertramm, A. Krtschil, A. Diez, J. Christen, and A. Frost, J. Cryst. Growth 267, 140 (2004), Copyright 2004, with permission from Elsevier.]

Image of FIG. 46.
FIG. 46.

Epitaxial relationships of a-plane ZnO grown on R-plane .

Image of FIG. 47.
FIG. 47.

Band structure and selection rules for the ZB and W structures. The crystal field and spin-orbit splittings are indicated schematically. The transitions which are allowed for various polarizations of photon electric-field vector with respect to the axis are indicated [after Birman (Ref. 296)].

Image of FIG. 48.
FIG. 48.

Reflection from ZnO at for (a) and (b) . Notice the PL lines for the data. [Reprinted from D. G. Thomas, J. Phys. Chem. Solids]15, 86 (1960), Copyright 1960, with permission from Elsevier.]

Image of FIG. 49.
FIG. 49.

Absorption coefficient and excitonic structure for an annealed (solid lines) and an unannealed (dotted line) sample at room temperature. The inset shows the absorption coefficient for the annealed samples at . [Reprinted with permission from J. F. Muth, R. M. Kolbas, A. K. Sharma, S. Oktyabrsky, and J. Narayan, J. Appl. Phys. 85, 7884 (1999). Copyright 1999, American Institute of Physics.] The exciton is misinterpreted as the exciton and the exciton-LO-phonon complex transitions as the exciton.

Image of FIG. 50.
FIG. 50.

Free-excitonic fine-structure region of the PL spectrum for a forming-gas-annealed ZnO substrate. [Reprinted with permission from A. Teke, Ü. Özgür, S. Doğan, X. Gu, H. Morkoç, B. Nemeth, J. Nause, and H. O. Everitt, Phys. Rev. B 70, 195207 (2004). Copyright 2004 by the American Physical Society.]

Image of FIG. 51.
FIG. 51.

Reflection spectra of a forming-gas-annealed ZnO substrate measured at with unpolarized light and with . The PL spectrum is also superimposed for comparison. [Reprinted with permission from A. Teke, Ü. Özgür, S. Doğan, X. Gu, H. Morkoç, B. Nemeth, J. Nause, and H. O. Everitt, Phys. Rev. B 70, 195207 (2004). Copyright 2004 by the American Physical Society.]

Image of FIG. 52.
FIG. 52.

Bound-excitonic region of the PL spectrum for a forming-gas-annealed ZnO substrate. [Reprinted with permission from A. Teke, Ü. Özgür, S. Doğan, X. Gu, H. Morkoç, B. Nemeth, J. Nause, and H. O. Everitt, Phys. Rev. B 70, 195207 (2004). Copyright 2004 by the American Physical Society.]

Image of FIG. 53.
FIG. 53.

PL spectrum for a forming-gas-annealed ZnO substrate in the TES region of the main bound-exciton lines. The inset shows the exciton binding energy vs donor binding energy. [Reprinted with permission from A. Teke, Ü. Özgür, S. Doğan, X. Gu, H. Morkoç, B. Nemeth, J. Nause, and H. O. Everitt, Phys. Rev. B 70, 195207 (2004). Copyright 2004 by the American Physical Society.]

Image of FIG. 54.
FIG. 54.

PL spectrum for a forming-gas-annealed ZnO substrate in the region where the donor-acceptor-pair transition and LO-phonon replicas are expected to appear. [Reprinted with permission from A. Teke, Ü. Özgür, S. Doğan, X. Gu, H. Morkoç, B. Nemeth, J. Nause, and H. O. Everitt, Phys. Rev. B 70, 195207 (2004). Copyright 2004 by the American Physical Society.]

Image of FIG. 55.
FIG. 55.

Temperature-dependent PL spectrum for a forming-gas-annealed ZnO substrate. The inset shows the PL in the DAP and LO-phonon replica regions up to . The spectrum for each temperature is displaced vertically for clarity. The room-temperature PL data are also included at the bottom. The lines drawn on some peaks are for guidance. [Reprinted with permission from A. Teke, Ü. Özgür, S. Doğan, X. Gu, H. Morkoç, B. Nemeth, J. Nause, and H. O. Everitt, Phys. Rev. B 70, 195207 (2004). Copyright 2004 by the American Physical Society.]

Image of FIG. 56.
FIG. 56.

Temperature-dependent peak positions of the -free exciton, and its 1LO- and 2LO-phonon replicas. Also shown are the temperature evolutions of the peak positions of the two major neutral-donor bound exciton transitions at 3.3606 and . The data were fitted using the Varshni equation and the LO-phonon replicas were fitted with the equation shown on the figure. [Reprinted with permission from A. Teke, Ü. Özgür, S. Doğan, X. Gu, H. Morkoç, B. Nemeth, J. Nause, and H. O. Everitt, Phys. Rev. B 70, 195207 (2004). Copyright 2004 by the American Physical Society.]

Image of FIG. 57.
FIG. 57.

Room-temperature time-resolved PL data for the as-received and the forming-gas-treated samples. [Reprinted with permission from A. Teke, Ü. Özgür, S. Doğan, X. Gu, H. Morkoç, B. Nemeth, J. Nause, and H. O. Everitt, Phys. Rev. B 70, 195207 (2004). Copyright 2004 by the American Physical Society.]

Image of FIG. 58.
FIG. 58.

Refractive index dispersion of ZnO for (a) and (b) below the fundamental absorption edge. The solid circles represent the spectroscopic ellipsometry data of Yoshikawa and Adachi (Ref. 326). The open circles and open triangles represent the data obtained by Bond (Ref. 17) and Mollwo (Ref. 16), respectively. [Reprinted with permission from H. Yoshikawa and S. Adachi, Jpn. J. Appl. Phys. 36, 6237 (1997). Copyright 1997, Institute of Pure and Applied Physics.]

Image of FIG. 59.
FIG. 59.

The ordinary and extraordinary refractive indices of the films (, 0.24, and 0.36). The solid curves are the least-squares fits to the first-order Sellmeier dispersion. The index of refraction of cubic MgO crystal measured by Stephens and Malitson (Ref. 23) is also plotted for comparison. [Reprinted with permission from C. W. Teng, J. F. Muth, Ü. Özgür, M. J. Bergmann, H. O. Everitt, A. K. Sharma, C. Jin, and J. Narayan, Appl. Phys. Lett. 76, 979 (2000). Copyright 2000 American Institute of Physics.]

Image of FIG. 60.
FIG. 60.

Room-temperature (RT) spectrally integrated PL for the ZnO samples normalized to the spontaneous emission. The inset shows the spectrally resolved PL for the sample for different excitation densities. The downward-pointing arrow in the inset indicates the exciton-exciton scattering-induced SE peak. [Reprinted with permission from Ü. Özgür, A. Teke, C. Liu, S.-J. Cho, H. Morkoç, and H. O. Everitt, Appl. Phys. Lett. 84, 3223 (2004). Copyright 2004, American Institute of Physics.]

Image of FIG. 61.
FIG. 61.

Normalized PL spectra for various excitation intensities at (a) room temperature and at (b) [Reprinted with permission from D. M. Bagnall, Y. F. Chen, Z. Zhu, T. Yao, M. Y. Shen, and T. Goto, Appl. Phys. Lett. 73, 1038 (1998). Copyright 1998, American Institute of Physics.]

Image of FIG. 62.
FIG. 62.

Room-temperature laser emission spectra. The inset shows clearly the resolved mode.s [Reprinted from D. M. Bagnall, Y. F. Chen, M. Y. Shen, Z. Zhu, T. Goto, and T. Yao, J. Cryst. Growth 184–185, 605 (1998), Copyright 1998, with permission from Elsevier.]

Image of FIG. 63.
FIG. 63.

Stimulated emission spectra for various excitation stripe lengths at room temperature. [Reprinted with permission from Y. Chen, N. T. Tuan, Y. Segawa, H.-J. Ko, S.-K. Hong, and T. Yao, Appl. Phys. Lett. 78, 1469 (2001). Copyright 2001, American Institute of Physics.]

Image of FIG. 64.
FIG. 64.

Optical gain spectrum of a ZnO epilayer at excitation densities of (a) , (b) , and (c) at RT. [Reprinted with permission from Y. Chen, N. T. Tuan, Y. Segawa, H.-J. Ko, S.-K. Hong, and T. Yao, Appl. Phys. Lett. 78, 1469 (2001). Copyright 2001, American Institute of Physics.]

Image of FIG. 65.
FIG. 65.

Lasing threshold as a function of film thickness. A excitation stripe was used. The thickness values were determined from the RHEED pattern intensity oscillations. [Reprinted from P. Yu, Z. K. Tang, G. K. L. Wong, M. Kawasaki, A. Ohtomo, H. Koinuma, and Y. Segawa, J. Cryst. Growth 184–185, 601 (1998), Copyright 1998, with permission from Elsevier.

Image of FIG. 66.
FIG. 66.

Spectra of emission from the ZnO powder when the excitation intensities are (from bottom to top) 400, 562, 763, 875, and . The thickness of the film of the ZnO powder is . The excitation area is about . The inset is a schematic diagram showing the formation of a closed-loop path for light through recurring scattering in the powder. [Reprinted with permission from H. Cao, Y. G. Zhao, S. T. Ho, E. W. Seelig, Q. H. Wang, and R. P. H. Chang, Phys. Rev. Lett. 82, 2278 (1999). Copyright 1999 by the American Physical Society.]

Image of FIG. 67.
FIG. 67.

PL intensity and PL peak position vs annealing temperature. [Reprinted with permission from S. Cho, J. Ma, Y. Kim, Y. Sun, G. K. L. Wong, and J. B. Ketterson, Appl. Phys. Lett. 75, 2761 (1991). Copyright 1999, American Institute of Physics.]

Image of FIG. 68.
FIG. 68.

Lasing spectra of the polycrystalline ZnO thin film obtained by oxidation of metallic Zn films. The threshold intensity for the lasing was . [Reprinted with permission from S. Cho, J. Ma, Y. Kim, Y. Sun, G. K. L. Wong, and J. B. Ketterson, Appl. Phys. Lett. 75, 2761 (1999). Copyright 1999, American Institute of Physics.]

Image of FIG. 69.
FIG. 69.

The dependences of the UV CL peak intensity and FWHM as a function of oxygen partial pressure (, electron-beam current of was used for excitation) [after Alivov et al. (Ref. 354)].

Image of FIG. 70.
FIG. 70.

Well width dependence of the stimulated emission threshold in the superlattices with (closed circles) and 0.26 (open circles). Stimulated emission did not take place for the films with below since the excitation energy is lower than the absorption energy. [Reprinted with permission from A. Ohtomo et al., Appl. Phys. Lett. 77, 2204 (2000). Copyright 2000, American Institute of Physics.]

Image of FIG. 71.
FIG. 71.

Room-temperature (RT) TRPL for the spontaneous emission (SPE) and the stimulated emission (SE) from the annealed ZnO samples. The inset shows the and RT TRPL data for the sample annealed at . [Reprinted with permission from Ü. Özgür, A. Teke, C. Liu, S.-J. Cho, H. Morkoç, and H. O. Everitt, Appl. Phys. Lett. 84, 3223 (2004). Copyright 2004, American Institute of Physics.]

Image of FIG. 72.
FIG. 72.

Calculated defect formation energy for the main native point defects in ZnO as a function of the Fermi level. Only the lowest formation-energy values are shown. The zero of the Fermi level is set to the top of the valence band. (a) Zinc-rich conditions and (b) oxygen-rich conditions. [Reprinted with permission from A. F. Kohan, G. Ceder, D. Morgan, and C. G. Van de Walle, Phys. Rev. B 61, 15019 (2000). Copyright 2000 by the American Physical Society.]

Image of FIG. 73.
FIG. 73.

PL spectra of undoped ZnO at different temperatures. The plots are vertically shifted for clarity. Between 30 and the DAP transition at decreases, and the adjacent transition at increases. [Reprinted from K. Thonke, T. Gruber, N. Teofilov, R. Schönfelder, A. Waag, and R. Sauer, Physica B 308–310, 945 (2001), Copyright 2001, with permission from Elsevier.]

Image of FIG. 74.
FIG. 74.

Low-temperature PL spectra of the (a) undoped and (b) nitrogen-doped ZnO films. [Reprinted with permission from A. Zeuner, H. Alves, D. M. Hofmann, B. K. Meyer, A. Hoffmann, U. Haboeck, M. Strassburg, and M. Dworzak, Phys. Status Solidi B 234, R7 (2002). Copyright 2002, Wiley.]

Image of FIG. 75.
FIG. 75.

GL band in ZnO at . The enlarged portion shows the fine structure at the high-energy side with the zero-phonon line at . [Reprinted with permission from R. Dingle, Phys. Rev. Lett. 23, 579 (1969). Copyright 1969 by the American Physical Society.]

Image of FIG. 76.
FIG. 76.

High-resolution spectra in the region of the zero-phonon line near . The intensity ratio is invariant in the temperature range of . [Reprinted with permission from R. Dingle, Phys. Rev. Lett. 23, 579 (1969). Copyright 1969 by the American Physical Society.]

Image of FIG. 77.
FIG. 77.

PL and PLE spectra near the zero-phonon transition of the GL associated with Cu in ZnO. [Reprinted with permission from P. J. Dean, D. J. Robbins, S. G. Bishop, J. A. Savage, and P. Porteous, J. Phys. C: Solid state Phys. 14, 2847 (1981). Copyright 1981, Institute of Physics.]

Image of FIG. 78.
FIG. 78.

A schematic diagram of the transitions in ZnO:Cu [after Dahan et al. (Ref. 376)].

Image of FIG. 79.
FIG. 79.

PL spectrum of undoped ZnO excited with the line of a HeCd laser . The inset shows a recombination model for the GL band peaked at . [Reprinted with permission from F. H. Leiter, H. R. Alves, A. Hofstaetter, D. M. Hoffmann, and B. K. Meyer, Phys. Status Solidi B 226, R4 (2001). Copyright 2001, Wiley.]

Image of FIG. 80.
FIG. 80.

PL spectrum of undoped bulk ZnO annealed at in air for . The solid (dashed) curve—after (before) HeCd irradiation for with an excitation density of . The excitation density during the measurements was .

Image of FIG. 81.
FIG. 81.

PL spectrum of undoped bulk ZnO at different temperatures. The sample was annealed at in air for . The excitation density is .

Image of FIG. 82.
FIG. 82.

PL spectra, at , for two ZnO samples, an undoped bulk sample and a N-doped, MBE-grown epitaxial layer. [Reprinted with permission from D. C. Look, D. C. Reynolds, C. W. Litton, R. L. Jones, D. B. Eason, and G. Cantwell, Appl. Phys. Lett. 81, 1830 (2002). Copyright 2002, American Institute of Physics.]

Image of FIG. 83.
FIG. 83.

(a) Calculated formation energies of as functions of the O chemical potential formed by atomic N (stripped off a or a molecule), NO, or molecule. is the Zn-rich limit condition and is the O-rich limit condition. (b) Calculated formation energies of a as functions of the O chemical potential for the defects formed by , , NO, and molecules. [Reprinted with permission from Y. Yan, S. B. Zhang, and S. T. Pantelides, Phys. Rev. Lett. 86, 5723 (2001). Copyright 2001 by the American Physical Society.]

Image of FIG. 84.
FIG. 84.

Crystal structure of a supercell for ZnO:(Ga, 2N). [Reprinted from T. Yamamoto, Thin Solid Films 420–421, 100 (2002), Copyright 2002, with permission from Elsevier.]

Image of FIG. 85.
FIG. 85.

Site-decomposed DOS of states at the N sites for (a) ZnO:N, (b) ZnO:(Al, 2N), (c) ZnO:(Ga, 2N), and (d) ZnO:(In, 2N). The dotted curve indicates the DOS at the N atom sites close to the reactive donor codopant; the solid curve indicates the DOS at the sites of next-nearest-neighbor N atoms. [Reprinted from T. Yamamoto and H. Katayama-Yoshida, J. Cryst. Growth 214/215, 552 (2000), Copyright 2000, with permission from Elsevier.]

Image of FIG. 86.
FIG. 86.

(a) Effect of oxygen partial pressure ratio on conduction type of codoped ZnO films. (b) Hole concentration, resistivity, and Hall mobility as a function of oxygen partial pressure. [Reprinted with permission from A. V. Singh, R. M. Mehra, A. Wakahara, and A. Yoshida, J. Appl. Phys. 93, 396 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 87.
FIG. 87.

Carrier concentration of phosphorus-doped ZnO thin films treated by RTA [Reprinted with permission from K.-K. Kim, H.-S. Kim, D.-K. Hwang, J.-H. Lim, and S.-J. Park, Appl. Phys. Lett. 83, 63 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 88.
FIG. 88.

Computed values of the Curie temperature for various -type semiconductors containing 5% of Mn and . [Reprinted with permission from T. Dietl, H. Ohno, F. Matsukura, J. Cibert, and D. Ferrand, Science 287, 1019 (2000). Copyright 2000 AAAS.]

Image of FIG. 89.
FIG. 89.

Stability of the ferromagnetic state in (a) Mn-, (b) Fe-, (c) Co-, and (d) Ni-doped ZnO as a function of the carrier concentration. The vertical axis is the energy difference between the ferromagnetic and the spin-glass state. A positive-energy difference indicates a more stable ferromagnetic state. [Reprinted with permission from K. Sato and H. Katayama-Yoshida, Semicond. Sci. Technol. 17, 367 (2002). Copyright 2002, Institute of Physics.]

Image of FIG. 90.
FIG. 90.

Stability of the ferromagnetic state in V-, Cr-, Mn-, Fe-, Co-, and Ni-doped ZnO without any additional carrier doping for different dopant concentrations. The vertical axis is the energy difference between the ferromagnetic and the spin-glass state. A positive energy difference indicates a more stable ferromagnetic state. [Reprinted with permission from K. Sato and H. Katayama-Yoshida, Semicond. Sci. Technol. 17, 367 (2002). Copyright 2002, Institute of Physics.]

Image of FIG. 91.
FIG. 91.

(a) Transmission spectra of the films measured at room temperature for various values. The numbers in the figures denote . The inset shows the photon energy dependence of squared absorption constant around the band gap . (b) Variation of with Mn content. The solid line is a fitted line expressed as . [Reprinted with permsission from T. Fukumura, Z. Jin, A. Ohtomo, H. Koinuma, and M. Kawasaki, Appl. Phys. Lett. 75, 3366 (1999). Copyright 1999, American Institute of Physics.]

Image of FIG. 92.
FIG. 92.

Magnetization normalized at for a film measured during ZFC and FC runs in various magnetic fields. The curves are vertically shifted as represented by the dotted lines. [Reprinted with permission from T. Fukumura, Z. Jin, M. Kawasaki, T. Shono, T. Hasegawa, S. Koshihara, and H. Koinuma, Appl. Phys. Lett. 78, 958 (2001). Copyright 2001, American Institute of Physics.]

Image of FIG. 93.
FIG. 93.

Solubility limit of TM ions in ZnO. The upper and lower limits of the error bars correspond, respectively, to the lowest of the pixels precipitated and the highest of the pixels without precipitation. The precipitated phases were also shown. [Reprinted with permission from Z. Jin et al., Appl. Phys. Lett. 78, 3824 (2001). Copyright 2001, American Institute of Physics.]

Image of FIG. 94.
FIG. 94.

(a) XRD pattern of the film, and (b) Co content dependency of the -axis lattice constant in films. [Reprinted with permission from K. Ueda, H. Tabata, and T. Kawai, Appl. Phys. Lett. 79, 988 (2001). Copyright 2001, American Institute of Physics.]

Image of FIG. 95.
FIG. 95.

Optical transmission spectra for the film. Typical absorption peaks of ions are indicated with arrows. [Reprinted from H. Saeki, H. Tabata, and T. Kawai, Solid State Commun. 120, 439 (2001), Copyright 2001, with permission from Elsevier.]

Image of FIG. 96.
FIG. 96.

Room-temperature UV absorbance spectra of (, 0.1, and 0.3) films. The absorbance spectra show a strong UV absorbance at . Note that the absorbance edge of the films blueshifts with increasing Mn content. [Reprinted with permission from S. W. Jung, S.-J. An, G.-C. Yi, C. U. Jung, S.-I. Lee, and S. Cho, Appl. Phys. Lett. 80, 4561 (2002). Copyright 2002, American Institute of Physics.]

Image of FIG. 97.
FIG. 97.

vs curve for the 3% Mn-implanted ZnO:Sn single-crystal sample at (a) and (b) . [Reprinted with permission from D. P. Norton, S. J. Pearton, A. F. Hebard, N. Theodoropoulou, L. A. Boatner, and R. G. Wilson, Appl. Phys. Lett. 82, 239 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 98.
FIG. 98.

Temperature dependence of the difference between field-cooled and zero-field-cooled magnetizations for (a) 3% and (b) 5% implanted Mn concentrations in -type ZnO:Sn single crystal. [Reprinted with permission from D. P. Norton, S. J. Pearton, A. F. Hebard, N. Theodoropoulou, L. A. Boatner, and R. G. Wilson, Appl. Phys. Lett. 82, 239 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 99.
FIG. 99.

(a) Optical absorbance spectra of films. a, b, c, d, and e correspond to , 0.05, 0.12, 0.18, and 0.25, respectively. (b) Variation of the band gap of films with . The data fit well in a second-order polynomial equation (solid line). [Reprinted with permission from A. Tiwari, C. Jin, A. Kvit, D. Kumar, J. F. Muth, and J. Narayan, Solid State Commun. 121, 371 (2002). Copyright 2002, American Institute of Physics.]

Image of FIG. 100.
FIG. 100.

Optical transmission spectrum of the film grown at . The absorption edges at 658, 616, and are indicated as 1, 2, and 3, respectively. [Reprinted with permission from S. Ramachandran, A. Tiwari, and J. Narayan, Appl. Phys. Lett. 84, 5255 (2004). Copyright 2004, American Institute of Physics.]

Image of FIG. 101.
FIG. 101.

Optical and structural properties of and alloy films mapped out in a plane of -axis length and room-temperature band-gap energy. The same curves for (In, Ga)N and (Al, Ga)N alloys are also shown. The alloy compositions are shown on the top axis. [Reprinted with permission from T. Makino, Y. Segawa, M. Kawasaki, A. Ohtomo, R. Shiroki, K. Tamura, T. Yasuda, and H. Koinuma, Appl. Phys. Lett. 78, 1237 (2001). Copyright 2001, American Institute of Physics.]

Image of FIG. 102.
FIG. 102.

Transmittance spectra of films measured at room temperature. The inset shows the band gap determined from the spectra assuming an dependence, where and are the absorption coefficient and the photon energy, respectively. [Reprinted with permission from A. Ohtomo, M. Kawasaki, T. Koida, K. Masubuchi, and H. Koinuma, Appl. Phys. Lett. 72, 2466 (1998). Copyright 1998, American Institute of Physics.]

Image of FIG. 103.
FIG. 103.

The PL energy position of the band edge and Mg concentration of the epilayers as a function of the to DEZn flux ratio. [Reprinted with permission from T. Gruber, C. Kirchner, R. Kling, F. Reuss, and A. Waag, Appl. Phys. Lett. 84, 5359 (2004). Copyright 2004, American Institute of Physics.].

Image of FIG. 104.
FIG. 104.

Concentration dependence of absorption spectra of epilayers obtained at room temperature. The curves, from right to left correspond to those of the samples with , 0.0013, 0.027, 0.043, and 0.073. [Reprinted with permission from T. Makino, Y. Segawa, M. Kawasaki, A. Ohtomo, R. Shiroki, K. Tamura, T. Yasuda, and H. Koinuma, Appl. Phys. Lett. 78, 1237 (2001). Copyright 2001, American Institute of Physics.]

Image of FIG. 105.
FIG. 105.

The experimental specific contact resistances as a function of temperature for unintentionally doped (open circles) and heavily Ga-doped (solid circles) ZnO [after Sheng et al. (Ref. 555)].

Image of FIG. 106.
FIG. 106.

Specific contact resistance vs carrier concentration of the as-deposited Ohmic contact measured at , and at 30 and , after annealing at for . [Reprinted with permission from K. Ip, Y. Heo, K. Balik, D. P. Norton, S. J. Pearton, and F. Ren, Appl. Phys. Lett. 84, 544 (2004). Copyright 2004, American Institute of Physics.]

Image of FIG. 107.
FIG. 107.

Spectral characteristics of the type-I (left: curve 1 at 77 K, curve 2 at 300 K) and type-II (right: 77 K) heterostructures. [Reprinted with permission from A. E. Tsurkan, N. D. Fedotova, L. V. Kicherman, and P. G. Pas'ko, Semiconductors 6, 1183 (1975). Copyright 1975, American Institute of Physics.]

Image of FIG. 108.
FIG. 108.

Emission spectra of the junction LED for several currents. The electric currents were (a) , (b) , (c) , and (d) , respectively. [Reprinted with permission from H. Ohta, K. Kawamura, M. Orita, M. Hirano, N. Sarukura, and H. Hosono, Appl. Phys. Lett. 77, 475 (2000). Copyright 2000, American Institute of Physics.]

Image of FIG. 109.
FIG. 109.

Electroluminescence spectrum of an heterostructure. [Reprinted with permission from Ya. I. Alivov, J. E. Van Nostrand, D. C. Look, M. V. Chukichev, and B. M. Ataev, Appl. Phys. Lett. 83, 2943 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 110.
FIG. 110.

Schematic diagram of the heterojunction LED structure [after Alivov et al. (Ref. 592)].

Image of FIG. 111.
FIG. 111.

Electroluminescence spectra of an heterostructure light-emitting diode at 300 and . [Reprinted with permission from Ya. I. Alivov, E. V. Kalinina. A. E. Cherenkov,D. C. Look, B. M. Ataev, A. K. Omaev, M. V. Chukichev, and D. M. Bagnall, Appl. Phys. Lett. 83, 4719 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 112.
FIG. 112.

Scanning electron microscope image of the grown double heterostructure [after Alivov et al. (Ref. 607)].

Image of FIG. 113.
FIG. 113.

Electroluminescence spectra of the double heterostructure diode at various forward biases [after Alivov et al. (Ref. 607)].

Image of FIG. 114.
FIG. 114.

Spectral response of the diode at several reverse-bias voltages. The device structure is also shown in the inset. [Reprinted with permission from H. Ohta, M. Hirano, K. Nakahara, H. Maruta, T. Tanabe, M. Kamiya, T. Kamiya, and H. Hosono, Appl. Phys. Lett. 83, 1029 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 115.
FIG. 115.

Room-temperature characteristics of heterojunctions [Reprinted with permission from Ya. I. Alivov, Ü. Özgür, S. Doğan, D. Johnstone, V. Avrutin, N. Onojima, C. Liu, J. Xie, Q. Fan, and H. Morkoç, Appl. Phys. Lett. 86, 241108 (2005). Copyright 2005, American Institute of Physics.]

Image of FIG. 116.
FIG. 116.

Spectral photoresponse of the photodiode structure at various reverse biases. [Reprinted with permission from Ya. I. Alivov, Ü. Özgür, S. Doğan, D. Johnstone, V. Avrutin, N. Onojima, C. Liu, J. Xie, Q. Fan, and H. Morkoç, Appl. Phys. Lett. 86, 241108 (2005). Copyright 2005, American Institute of Physics.]

Image of FIG. 117.
FIG. 117.

Current-voltage characteristics of the ZnO MIS diode. [Reprinted from Ya. I. Alivov, D. C. Look, B. M. Ataev, M. V. Chukichev, V. V. Mamedov, V. I. Zinenko, Yu. A. Agafonov, and A. N. Pustovit, Solid-State Electron. 48, 2343 (2004), Copyright 2004, with permission from Elsevier.]

Image of FIG. 118.
FIG. 118.

Room-temperature (a) EL and (b) CL spectra of the MIS diode and ZnO layer, respectively. [Reprinted from Ya. I. Alivov, D. C. Look, B. M. Ataev, M. V. Chukichev, V. V. Mamedov, V. I. Zinenko, Yu. A. Agafonov, and A. N. Pustovit, Solid-State Electron. 48, 2343 (2004), Copyright 2004, with permission from Elsevier.]

Image of FIG. 119.
FIG. 119.

The schematics of a typical TTFT structure. [Reprinted with permission from R. L. Hoffman, B. J. Norris, and J. F. Wager, Appl. Phys. Lett. 82, 733 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 120.
FIG. 120.

Electrical characteristics of TTFT: (a) drain-current–drain-voltage characteristics; (b) transfer characteristics and gate leakage current for a TTFT with a width-to-length ratio of 10:1 for . [Reprinted with permission from R. L. Hoffman, B. J. Norris, and J. F. Wager, Appl. Phys. Lett. 82, 733 (2003). Copyright 2003, American Institute of Physics.]

Image of FIG. 121.
FIG. 121.

A schematic diagram of the horizontal tube furnace for growth of ZnO nanostructures by the solid-vapor phase process [after Wang (Ref. 619)].

Image of FIG. 122.
FIG. 122.

Scanning electron microscope images of ZnO nanowire arrays grown on sapphire substrates [(a)–(e)]. A top view of the well-faceted hexagonal nanowire tips is shown in (e). (f) High-resolution TEM image of an individual ZnO nanowire showing its ⟨0001⟩ growth direction. [Reprinted with permission from M. H. Huang, S. Mao, H. Feick, H. Yan, Y. Wu, H. Kind, E. Weber, R. Russo, and P. Yang, Science 292, 1897 (2001). Copyright 2001 AAAS.]

Image of FIG. 123.
FIG. 123.

Emission spectra from nanowire arrays below (line a) and above (line b and inset) the lasing threshold. The pump power levels for these spectra are 20, 100, and , respectively. The spectra are offset for easy comparison. [Reprinted with permission from M. H. Huang, S. Mao, H. Feick, H. Yan, Y. Wu, H. Kind, E. Weber, R. Russo, and P. Yang, Science 292, 1897 (2001). Copyright 2001 AAAS.]

Image of FIG. 124.
FIG. 124.

FE-SEM (a) plan-view and (b) tilted images of ZnO nanorods with a mean diameter of and (c) tilted and (d) cross-sectional images of ZnO nanorods with a mean diameter of . In (c), hexagon-shaped pyramids with flat terraces and steps are seen at the ends of the nanorods. [Reprinted with permission from W. I. Park, D. H. Kim, S.-W. Jung, and G.-C. Yi, Appl. Phys. Lett. 80, 4232 (2002). Copyright 2002, American Institute of Physics.]

Image of FIG. 125.
FIG. 125.

XRD (a) scan, (b) rocking curve, and (c) azimuthal scan measurement results of ZnO nanorods. From the XRD scan data, only two peaks are shown at 34.32° and 72.59° which correspond to ZnO (002) and (004) peaks, respectively. The rocking curve also shows a FWHM value of 0.6°. A sixfold symmetry in the -scan data is also observed, indicating in-plane alignment of the nanorods. [Reprinted with permission from W. I. Park, D. H. Kim, S.-W. Jung, and G.-C. Yi, Appl. Phys. Lett. 80, 4232 (2002). Copyright 2002, American Institute of Physics.]

Image of FIG. 126.
FIG. 126.

(a) Schematic side view and (b) field-emission scanning electron microscopy image of a ZnO nanorod FET device. ZnO nanorod FETs with back gate geometry were fabricated on by deposition of metal electrodes for source-drain contacts on the nanorod ends. [Reprinted with permission from W. I. Park, J. S. Kim, G.-C. Yi, M. H. Bae, and H.-J. Lee, Appl. Phys. Lett. 85, 5052 (2004). Copyright 2004, American Institute of Physics.]

Image of FIG. 127.
FIG. 127.

Source-drain current vs gate voltage curves (solid line) as a function of source-drain voltage and log scale plot (open circles) of for a ZnO single nanorod FET after polyimide coating on the device. [Reprinted with permission from W. I. Park, J. S. Kim, G.-C. Yi, M. H. Bae, and H.-J. Lee, Appl. Phys. Lett. 85, 5052 (2004). Copyright 2004, American Institute of Physics.]

Image of FIG. 128.
FIG. 128.

(a) Low-magnification SEM image of the as-synthesized ZnO nanorings. (b) High-magnification SEM image of a freestanding single-crystal ZnO nanoring, showing uniform and perfect geometrical shape. The ring diameter is , the thickness of the ring is , and the width of the ring shell is . [Reprinted with permission from X. Y. Kong, Y. Ding, R. Yang, and Z. L. Wang, Science 303, 1348 (2004). Copyright 2004 AAAS.]

Image of FIG. 129.
FIG. 129.

Transmission electron microscopy image of a double-sided comb structure, showing the distinct arrays of nanotips and nanofingers on the two sides. The inset is the corresponding electron-diffraction pattern and the enlargements of the two selected areas, as indicated. [Reprinted with permission from Z. L. Wang, X. Y. Kong, and J. M. Zuo, Phys. Rev. Lett. 91, 185502 (2003). Copyright 2003 by the American Physical Society.]

Image of FIG. 130.
FIG. 130.

SEM images of ZnO tubes formed at under different reactor pressures. (a) Top image of the tubes obtained at . [(b)–(d)] SEM images taken with an inclination angle of the tubes obtained at 0.3, 0.6, and , respectively. [Reprinted with permission from B. P. Zhang, N. T. Binh, K. Wakatsuki, Y. Segawa, Y. Yamada, N. Usami, M. Kawasaki, and H. Koinuma, Appl. Phys. Lett. 84, 4098 (2004). Copyright 2004, American Institute of Physics.]

Image of FIG. 131.
FIG. 131.

SEM images of bunches of ZnO nanopropeller arrays rooted at substrate grown at various temperatures: (a) a single column of the as-synthesized ZnO nanopropeller arrays; (b) front view of a column of ZnO nanopropeller arrays with nanowires at the central axis, which was collected from a lower-temperature zone ; (c) a column of ZnO nanopropeller arrays with uniform nanoribbon shape and smoother surface, which was collected from a medium-temperature zone ; and (d) a column of ZnO nanopropeller arrays with long nanoribbons, which was collected from a higher-temperature zone . [Reprinted with permission from P. X. Gao, and Z. L. Wang, Appl. Phys. Lett. 84, 2883 (2004). Copyright 2004, American Institute of Physics.]

Image of FIG. 132.
FIG. 132.

Representative SEM images of ZnO nanostructures: (a) ZnO prepared from Zn, (b) ZnO prepared from ZnO:C, and (c) ZnO prepared from . [Reprinted with permission from A. B. Djurišić, Y. H. Leung, W. C. H. Choy, K. W. Cheah, and W. K. Chan, Appl. Phys. Lett. 84, 2635 (2004). Copyright 2004, American Institute of Physics.]

Tables

Generic image for table
Table I.

Theoretical and experimental pressure parameters of ZnO.

Generic image for table
Table II.

Measured and calculated lattice constants and parameter of ZnO.

Generic image for table
Table III.

Calculated and measured energy gaps , cation -band positions , and anion valence bandwidths (in eV) of ZnO [Vogel et al. (Ref. 89)]. LDA-PP, local-density approximation pseudopotential; LDA-SIC-PP, local-density approximation self-interaction-corrected pseudopotential.

Generic image for table
Table IV.

Some mechanical properties of ZnO obtained by several experimental techniques and theoretical calculations.

Generic image for table
Table V.

Phonon mode frequencies (in units of ) of wurtzite ZnO at the center of the Brillouin zone obtained from infrared spectroscopic ellipsometry (IRSE) and RS measurements in comparison with theoretical predictions.

Generic image for table
Table VI.

Thermal conductivity, (W/cm K), at multiple positions of bulk ZnO samples with various surface treatments (Ref. 138).

Generic image for table
Table VII.

A compilation of XRD results, electron mobilities, and corresponding carrier concentration obtained in nominally undoped bulk and thin-film ZnO deposited on different substrates by various growth techniques.

Generic image for table
Table VIII.

Lattice parameters of a number of the prospective substrate materials for ZnO.

Generic image for table
Table IX.

Structural and optical parameters for the ZnO samples obtained from AFM, XRD, and PL measurements.

Generic image for table
Table X.

Excitonic peak energies (eV) in ZnO single crystals.

Generic image for table
Table XI.

Bound exciton peak energies (eV) in ZnO single crystals.

Generic image for table
Table XII.

TRPL decay time constants and amplitude ratios for the ZnO samples at two different excitation energy densities. FX and DBE denote the free and donor-bound excitons, respectively [Teke et al. (Ref. 299)].

Generic image for table
Table XIII.

Some values of the refractive indices of ZnO at near the absorption edge [Park and Schneider (Ref. 24)].

Generic image for table
Table XIV.

Sellmeier coefficients for films [After Teng et al. (Ref. 328)].

Generic image for table
Table XV.

Static and high-frequency dielectric constants of ZnO.

Generic image for table
Table XVI.

Cauchy model parameters for the alloy system [Schmidt et al. (Ref. 329)].

Generic image for table
Table XVII.

Calculated nearest-neighbor bond lengths, the defect energy levels for negatively charged substitutional impurities, and the energy required to form the positively charged center from the substitutional acceptors [Park et al. (Ref. 419)].

Generic image for table
Table XVIII.

Ohmic contacts to -type ZnO for various metallization schemes. -TLM stands for circular transmission line method.

Generic image for table
Table XIX.

Schottky contacts to -type ZnO.

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2005-08-30
2014-04-16
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: A comprehensive review of ZnO materials and devices
http://aip.metastore.ingenta.com/content/aip/journal/jap/98/4/10.1063/1.1992666
10.1063/1.1992666
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