Electronic structure and optical properties of N vacancy and O filling on n-GaN (0001) surface
| Autor: | Lei Liu, Sihao Xia, Yu Diao, Feifei Lu, Shu Feng |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Materials science Doping 02 engineering and technology Electronic structure Conductivity 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Molecular physics X-ray photoelectron spectroscopy Vacancy defect 0103 physical sciences Atom Density of states General Materials Science Density functional theory Electrical and Electronic Engineering 0210 nano-technology |
| Zdroj: | Superlattices and Microstructures. 118:160-169 |
| ISSN: | 0749-6036 |
| Popis: | In the X-ray photoelectron spectroscopy experiment, we observed that the valence band spectrum of the n-GaN (0001) surface appeared a bump near 1.9 eV after Ar etching and the N/Ga ratio became smaller, while the bump disappeared upon exposure to air. In order to analyze this phenomenon theoretically, we mainly study the electronic structure and optical properties of n-GaN (0001) surface with N vacancy and filled with O atom based on the first principles of density functional theory. The results suggest that the n-GaN (0001) surface exhibits semi-metallic property. The introduction of N vacancy reduces the n-type conductivity, whereas the filling of O atom enhances conductivity. The density of state near −1.9eV shows a good agreement between the clean n-type surface and the O-atom-filled surface, while the N vacancy surface has a higher density of states, which is similar to the experimentally observed phenomenon. It is also found that the existence of N vacancy reduces the photoemission properties of the n-GaN (0001) surface and the filling of O atom alleviates the defect caused by vacancy. This study shows that N vacancy increases the doping difficulty of n-type GaN films, however, the filling of O atom may compensate for the diminished photoelectric properties induced by N vacancy and be conducive to prepare high-performance optoelectronic devices with the contact of n-GaN and metal. |
| Databáze: | OpenAIRE |
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