Deep level optical and thermal spectroscopy of traps in n-GaN grown by ammonia molecular beam epitaxy
- Department of Electrical and Computer Engineering, Ohio State University, Columbus, Ohio 43210 (United States)
- Materials and Electrical and Computer Engineering Departments, University of California, Santa Barbara, California 93106 (United States)
The incorporation of deep level defects in n-type GaN grown by ammonia-based molecular beam epitaxy (MBE) is studied via systematic adjustment of the NH{sub 3}/Ga flux ratio. Deep level optical and transient spectroscopies, which together enable deep level detection throughout the GaN bandgap, reveal defect states whose individual concentrations vary with the NH{sub 3}/Ga flux ratio. A general trend of lower concentration for deep levels at E{sub C}-3.28, E{sub C}-1.28, E{sub C}-0.62, and E{sub C}-0.25 eV with higher NH{sub 3}/Ga flux ratio was observed, with the strongest reduction at the E{sub C}-0.25 eV level, consistent with expectations for a V{sub N}-related defect. The known C{sub N} impurity state at E{sub C}-3.28 eV and suspected C{sub I}-related state at E{sub C}-1.28 eV also showed a moderate decrease in concentration at the higher NH{sub 3}/Ga flux ratio. In contrast, the V{sub Ga}-related defect at E{sub C}-2.62 eV was insensitive to the NH{sub 3}/Ga flux ratio over the range studied here. Taken together, ammonia-MBE GaN has deep level defects with different sensitivities in flux ratios suggestive of independent physical sources. However, the total trap concentrations were significantly reduced for higher NH{sub 3}/Ga flux ratios in n-type GaN grown by ammonia-MBE under the range of growth conditions used in this study, suggesting that higher NH{sub 3}/Ga flux ratios will generate higher electronic quality GaN material when using ammonia-based MBE for device applications.
- OSTI ID:
- 21175584
- Journal Information:
- Applied Physics Letters, Vol. 93, Issue 11; Other Information: DOI: 10.1063/1.2981571; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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