1. Role of Native Defects in Fe-Doped β-Ga 2 O 3.
- Author
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Zeng, Hui, Wu, Meng, Gao, Haixia, Wang, Yuansheng, Xu, Hongfei, Cheng, Meijuan, and Lin, Qiubao
- Subjects
DOPING agents (Chemistry) ,INFRARED absorption ,IRON ,CONDUCTION bands ,LIGHT absorption ,FERMI level ,DENSITY functional theory - Abstract
Iron impurities are believed to act as deep acceptors that can compensate for the n-type conductivity in as-grown Ga
2 O3 , but several scientific issues, such as the site occupation of the Fe heteroatom and the complexes of Fe-doped β-Ga2 O3 with native defects, are still lacking. In this paper, based on first-principle density functional theory calculations with the generalized gradient approximation approach, the controversy regarding the preferential Fe incorporation on the Ga site in the β-Ga2 O3 crystal has been addressed, and our result demonstrates that Fe dopant is energetically favored on the octahedrally coordinated Ga site. The structural stabilities are confirmed by the formation energy calculations, the phonon dispersion relationships, and the strain-dependent analyses. The thermodynamic transition level Fe3+ /Fe2+ is located at 0.52 eV below the conduction band minimum, which is consistent with Ingebrigtsen's theoretical conclusion, but slightly smaller than some experimental values between 0.78 eV and 1.2 eV. In order to provide direct guidance for material synthesis and property design in Fe-doped β-Ga2 O3 , the defect formation energies, charge transitional levels, and optical properties of the defective complexes with different kinds of native defects are investigated. Our results show that VGa and Oi can be easily formed for the Fe-doped β-Ga2 O3 crystals under O-rich conditions, where the +3 charge state FeGa Gai and −2 charge state FeGa Oi are energetically favorable when the Fermi level approaches the valence and conduction band edges, respectively. Optical absorption shows that the complexes of FeGa Gai and FeGa VGa can significantly enhance the optical absorption in the visible-infrared region, while the energy-loss function in the β-Ga2 O3 material is almost negligible after the extra introduction of various intrinsic defects. [ABSTRACT FROM AUTHOR]- Published
- 2023
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