No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
Electronic structure of Al- and Ga-doped ZnO films studied by hard X-ray photoelectron spectroscopy
1. T. Hanada, “Oxide and Nitride Semiconductors,” in Advanced Materials Research, edited by T. Yao and S.-K. Hong (Springer, Berlin, 2009), p. 1.
2. M. Gabás, A. Landa-Cánovas, J. L. Costa-Krämer, F. Agulló-Rueda, A. R. González-Elipe, P. Díaz-Carrasco, J. Hernández-Moro, I. Lorite, P. Herrero, P. Castillero, A. Barranco, and J. Ramón Ramos-Barrado, J. Appl. Phys. 113, 163709 (2013).
3. M. Gabás, P. Torelli, N. T. Barrett, M. Sacchi, F. Bruneval, Y. Cui, L. Simonelli, P. Díaz-Carrasco, and J. R. Barrado, “Direct observation of Al-doping-induced electronic states in the valence band and band gap of ZnO films,” Phys. Rev. B 84, 153303 (2011).
4. J.-Y. Noh, H. Kim, Y.-S. Kim, and C. H. Park, “Electron doping limit in Al-doped ZnO by donor-acceptor interactions,” J. Appl. Phys. 113, 153703 (2013).
5. M. Sacchi, F. Offi, P. Torelli, A. Fondacaro, C. Spezzani, M. Cautero, G. Cautero, S. Huotari, M. Grioni, R. Delaunay, M. Fabrizioli, G. Vankó, G. Monaco, G. Paolicelli, G. Stefani, and G. Panaccione, “Quantifying the effective attenuation length in high-energy photoemission experiments,” Phys. Rev. B 71, 155117 (2005).
6. G. Panaccione and K. Kobayashi, “Hard X-ray photoemission spectroscopy: Variable depth analysis of bulk, surface and interface electronic properties,” Surf. Sci. 606, 125–129 (2012).
7. P. Torelli, M. Sacchi, G. Cautero, M. Cautero, B. Krastanov, P. Lacovig, P. Pittana, R. Sergo, R. Tommasini, A. Fondacaro, F. Offi, G. Paolicelli, G. Stefani, M. Grioni, R. Verbeni, G. Monaco, and G. Panaccione, “Experimental setup for high energy photoemission using synchrotron radiation,” Rev. Sci. Instrum. 76, 023909 (2005).
10. J. H. Scofield, “Theoretical photoionization cross sections from 1 to 1500 keV,” Report UCRL–51326, Livermore, 1973.
11. I. Ivanov and J. Pollman, “Electronic structure of ideal and relaxed surfaces of ZnO: A prototype ionic wurtzite semiconductor and its surface properties,” Phys. Rev. B 24, 7275–7296 (1981).
13. M. Gabás, N. Barrett, J. Ramos-Barrado, S. Gota, T. Rojas, and M. López-Escalante, “Chemical and electronic interface structure of spray pyrolysis deposited undoped and Al-doped ZnO thin films on a commercial Cz-Si solar cell substrate,” Sol. Energy Mater. Sol. Cells 93, 1356–1365 (2009).
15. D. O. Demchenko, B. Earles, H. Y. Liu, V. Avrutin, N. Izyumskaya, U. Özgür, and H. Morkoç, “Impurity complexes and conductivity of Ga-doped ZnO,” Phys. Rev. B 84, 075201 (2011).
16. J. U. Brehm, M. Winterer, and H. Hahn, “Synthesis and local structure of doped nanocrystalline zinc oxides,” J. Appl. Phys. 100, 064311 (2006).
17. Y. W. Heo, D. P. Norton, and S. J. Pearton, “Origin of green luminescence in ZnO thin film grown by molecular-beam epitaxy,” J. Appl. Phys. 98, 073502 (2005).
18. Y.-S. Kim and C. Park, “Rich variety of defects in ZnO via an attractive interaction between O vacancies and Zn interstitials: Origin of n-type doping,” Phys. Rev. Lett. 102, 086403 (2009).
20. M. Bazzani, A. Neroni, A. Calzolari, and A. Catellani, “Optoelectronic properties of Al:ZnO: Critical dosage for an optimal transparent conductive oxide,” Appl. Phys. Lett. 98, 121907 (2011).
Article metrics loading...
Al- and Ga-doped sputtered ZnO films (AZO, GZO) are semiconducting and metallic, respectively, despite the same electronic valence structure of the dopants. Using hard X-ray photoelectron spectroscopy we observe that both dopants induce a band in the electronic structure near the Fermi level, accompanied by a narrowing of the Zn 3d/O 2p gap in the valence band and, in the case of GZO, a substantial shift in the Zn 3d. Ga occupies substitutional sites, whereas Al dopants are in both substitutional and interstitial sites. The latter could induce O and Zn defects, which act as acceptors explaining the semiconducting character of AZO and the lack of variation in the optical gap. By contrast, mainly substitutional doping is consistent with the metallic-like behavior of GZO.
Full text loading...
Most read this month