APL: Structural, Mechanical, Thermodynamic, and Optical Properties of Condensed Matter

Effects of well width and growth temperature on optical and structural characteristics of AlN/GaN superlattices grown by metal-organic chemical vapor deposition

C. Bayram, N. Pere-laperne, and M. Razeghi
AlN/GaN superlattices (SLs) employing various well widths (from 1.5 to 7.0 nm) are grown by metal-organic chemical vapor deposition technique at various growth temperatures (T) (from 900 to 1035 degrees C). The photoluminescence (PL), x-ray diffraction, and intersubband (ISB) absorption characteris ... [Appl. Phys. Lett. 95, 201906 (2009)] published Fri Nov 20, 2009.

Dynamical and quasistatic structural relaxation paths in PdNiP glass

A. Kahl, T. Koeppe, D. Bedorf, R. Richert, M. L. Lind et al.
By sequential heat treatment of a PdNiP metallic glass at temperatures and durations for which alpha-relaxation is not possible, dynamic, and quasistatic relaxation paths below the glass transition are identified via ex situ ultrasonic measurements following each heat treatment. The dynamic relaxati ... [Appl. Phys. Lett. 95, 201903 (2009)] published Thu Nov 19, 2009.

Electronic structure of substitutional Mn in epitaxial InMnSb film

N. D. Parashar, D. J. Keavney, and B. W. Wessels
The magnetic and electronic structure of Mn in InMnSb ferromagnetic semiconductor thin film was studied by x-ray absorption spectroscopy and x-ray magnetic circular dichroism. Comparison with atomic multiplet calculations suggests that manganese substitutes on sites with tetrahedral symmetry. Strong ... [Appl. Phys. Lett. 95, 201905 (2009)] published Thu Nov 19, 2009.

Photoluminescence enhancement of Er-doped silica containing Ge nanoclusters

J. Guzman, S. J. Shin, C. Y. Liao, C. W. Yuan, P. R. Stone et al.
The photoluminescence (PL) of Er-doped silica films containing Ge nanoclusters synthesized by ion implantation was investigated. The area of the 1540 nm Er PL peak was enhanced by up to a factor of 200 by the addition of Ge nanoclusters. The PL enhancement was found to be proportional to the concent ... [Appl. Phys. Lett. 95, 201904 (2009)] published Thu Nov 19, 2009.

Synthesis and characterization of nanoporous PtNi alloys

Hongqi Li, Amit Misra, Jon K. Baldwin, and S. T. Picraux
Two nanoporous PtNi alloys were synthesized by dealloying ternary amorphous SiPtNi precursors. Both foams have nearly the same composition, ligament diameter size, and density. However, their ligament patterns are different, depending on the microstructure of precursors. The difference in morphology ... [Appl. Phys. Lett. 95, 201902 (2009)] published Mon Nov 16, 2009.

Measurement of anharmonicity of phonons in the negative thermal expansion compound Zn(CN) by high pressure inelastic neutron scattering

R. Mittal, S. L. Chaplot, and H. Schober
Zn(CN) is known to have an isotropic negative thermal expansion (NTE) coefficient (about 51 x 10 K) over 10370 K that is twice as large as that of ZrWO. We have measured the pressure dependence of the phonon spectra up to 30 meV from a polycrystalline sample of Zn(CN) at pressures of 0, 0.3, 1.9, a ... [Appl. Phys. Lett. 95, 201901 (2009)] published Mon Nov 16, 2009.

Giant changes in atomic dynamics on microalloying metallic melt

S. M. Chathoth, B. Damaschke, J. P. Embs, and K. Samwer
We report unexpectedly strong variations in the relaxational dynamics in a glass-forming metallic melt while microalloying. Analysis of quasielastic neutron scattering data revealed that changes in the values of stretching of the self-correlation function and the temperature dependence of self-diffu ... [Appl. Phys. Lett. 95, 191907 (2009)] published Fri Nov 13, 2009.

Robust atomic resolution imaging of light elements using scanning transmission electron microscopy

S. D. Findlay, N. Shibata, H. Sawada, E. Okunishi, Y. Kondo et al.
We show that an annular detector placed within the bright field cone in scanning transmission electron microscopy allows direct imaging of light elements in crystals. In contrast to common high angle annular dark field imaging, both light and heavy atom columns are visible simultaneously. In contras ... [Appl. Phys. Lett. 95, 191913 (2009)] published Fri Nov 13, 2009.

Study of minority carrier diffusion length in multicrystalline silicon solar cells using photoassisted Kelvin probe force microscopy

Masaki Takihara, Takuji Takahashi, and Toru Ujihara
We evaluated the minority carrier diffusion length in multicrystalline silicon solar cells by means of photoassisted Kelvin probe force microscopy to investigate the influence of the multicrystalline material grains and the grain boundaries on solar cell performance. We observed a reduction in the d ... [Appl. Phys. Lett. 95, 191908 (2009)] published Fri Nov 13, 2009.

Water vapor interaction with silicon oxide films thermally grown on 6H-SiC and on Si

G. V. Soares, I. J. R. Baumvol, S. A. Correa, C. Radtke, and F. C. Stedile
Thermally induced incorporation of isotopically labeled water vapor (D O) species in 7 nm thick SiO films thermally grown on 6H-SiC(0001) and on Si(001) were investigated. Higher incorporation of hydrogen and higher isotopic exchange were observed in SiO/SiC as compared to SiO/Si, at temperatures ab ... [Appl. Phys. Lett. 95, 191912 (2009)] published Fri Nov 13, 2009.

Transformation pathways in the solid-solid phase transitions of iron nanowires

Luis Sandoval and Herbert M. Urbassek
Using molecular dynamics simulations, we study the solid-solid phase transitions induced by strain in Fe nanowires. These show an intricate dependence on the crystallographic orientation of the wire. oriented nanowires exhibit a bcc-->fcc transition and preferably follow the NishiyamaWassermann pat ... [Appl. Phys. Lett. 95, 191909 (2009)] published Fri Nov 13, 2009.

Practical approach for a rod-connected diamond photonic crystal operating at optical wavelengths

Kanna Aoki
Production of a rod-connected diamond (RCD) photonic crystal structure in a semiconductor material is proposed. Periodic shifting of only one building block can create a complicated three-dimensional network, with a RCD structure exhibiting a full bandgap as wide as 0.20 on a gap/midgap (Deltaomega/ ... [Appl. Phys. Lett. 95, 191910 (2009)] published Fri Nov 13, 2009.

Femtosecond carrier dynamics and saturable absorption in graphene suspensions

Sunil Kumar, M. Anija, N. Kamaraju, K. S. Vasu, K. S. Subrahmanyam et al.
Nonlinear optical properties and carrier relaxation dynamics in graphene, suspended in three different solvents, are investigated using femtosecond (80 fs pulses) Z-scan and degenerate pump-probe spectroscopy at 790 nm. The results demonstrate saturable absorption property of graphene with a nonline ... [Appl. Phys. Lett. 95, 191911 (2009)] published Fri Nov 13, 2009.

Dramatic excitation dependence of strong and stable blue luminescence of ZnO hollow nanoparticles

Haibo Zeng, Shikuan Yang, Xiaoxia Xu, and Weiping Cai
Strong and stable blue luminescence was obtained from ZnO hollow nanoparticles. Significantly, dramatic excitation dependence was observed for blue emissions of ZnO: (1) band-gap energy (E) is the optimal excitation energy but smaller energies are still effective; (2) there exist several fixed emitt ... [Appl. Phys. Lett. 95, 191904 (2009)] published Thu Nov 12, 2009.

Size effect on the lattice parameters of nanocrystalline anatase

Md. Imteyaz Ahmad and S. S. Bhattacharya
Crystallite size dependence on the lattice parameters of nanocrystalline anatase was examined by x-ray diffraction pattern analysis, x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The lattice parameter a increased while the parameter c decreased with reducing crystallite sizes. Howe ... [Appl. Phys. Lett. 95, 191906 (2009)] published Thu Nov 12, 2009.

Photoreflectance and Fourier transform infrared spectroscopy study of intersubband transitions of a ZnCdSe/ZnCdMgSe asymmetric coupled quantum well structure for quantum cascade laser application

J. D. Wu, C. T. Huang, Y. S. Huang, W. O. Charles, A. Shen et al.
Photoreflectance (PR) and Fourier transform infrared (FTIR) spectroscopy were used to study the intersubband (ISB) transitions of a ZnCdSe/ZnCdMgSe asymmetric coupled quantum well (ACQW) structure for quantum cascade laser (QCL) application. The PR spectrum revealed a wide range of possible optical ... [Appl. Phys. Lett. 95, 191905 (2009)] published Thu Nov 12, 2009.

Local chemical states and thermal stabilities of nitrogen dopants in ZnO film studied by temperature-dependent x-ray photoelectron spectroscopy

X. H. Li, H. Y. Xu, X. T. Zhang, Y. C. Liu, J. W. Sun et al.
Local chemical states and thermal stabilities of N dopants in ZnO:N film are investigated by temperature-dependent x-ray photoelectron spectroscopy. Different types of N local states are detected, including N molecules occupying O sites [(N)], NO species, substitutional N atoms in O- and N-rich loca ... [Appl. Phys. Lett. 95, 191903 (2009)] published Wed Nov 11, 2009.

Temperature dependence of ministop band in double-slots photonic crystal waveguides

Kaiyu Cui, Yidong Huang, Gengyan Zhang, Yongzhuo Li, Xuan Tang et al.
We proposed and fabricated a double-slots photonic crystal waveguides (PCWGs) structure formed by introducing two slots into PCWGs with air-bridge structure on silicon-on-insulator substrate. The mode characteristics of double-slots PCWGs were investigated theoretically and experimentally. The trans ... [Appl. Phys. Lett. 95, 191901 (2009)] published Tue Nov 10, 2009.

Arrhenius behavior of hydrocarbon fuel photochemical reaction rates by thermal lens spectroscopy

N. G. C. Astrath, F. B. G. Astrath, J. Shen, J. Zhou, K. H. Michaelian et al.
The temperature dependence of thermo-optical and photochemical reaction properties of hydrocarbon fuels is investigated using thermal lens spectroscopy. We consider the time dependence of the absorption coefficient due to the photoinduced chemical reaction (PCR) and species diffusion to evaluate non ... [Appl. Phys. Lett. 95, 191902 (2009)] published Tue Nov 10, 2009.

Optical properties of 1.3 [mu]m InAs/GaAs bilayer quantum dots with high areal density

C. Y. Ngo, S. F. Yoon, D. R. Lim, Vincent Wong, and S. J. Chua
InAs/GaAs bilayer quantum dots (BQDs) are interesting structures for long wavelength emission due to its ability to tune the areal density and dot size separately. However, the need for two sets of growth rate and temperature for the respective QD layers complicates the growth procedures. Furthermor ... [Appl. Phys. Lett. 95, 181913 (2009)] published Fri Nov 6, 2009.

Aging of AlGaN quantum well light emitting diode studied by scanning near-field optical spectroscopy

A. Pinos, S. MarcinkeviCius, J. Yang, Y. Bilenko, M. Shatalov et al.
Emission from a 285 nm AlGaN quantum well light emitting diode has been studied by scanning near-field optical spectroscopy. The scans revealed micrometer-size domainlike areas emitting with a higher intensity and at a longer wavelength; presumably, because of a lower AlN molar fraction in these reg ... [Appl. Phys. Lett. 95, 181914 (2009)] published Fri Nov 6, 2009.