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It was expected that the properties of intrinsic point defects are simple in the binary semiconductor SbSe. we show using first-principles calculations that the intrinsic defects in this quasi-one-dimensional (Q1D) semiconductor are unexpectedly complicated and different from those in conventional photovoltaic semiconductors such as CdTe or GaAs. Firstly, the same type of defects located on non-equivalent atomic sites can have very different properties due to the low symmetry of the Q1D structure, which makes the properties of point defects complicated although there are only a few point defects. Secondly, the uncommon defects such as the cation-replace-anion antisite Sb, anion-replace-cation antisite Se, and even two-anion-replace-one-cation antisite 2Se, which are difficult to form in CdTe and GaAs, can have high concentration and even be dominant in SbSe due to the weak van der Waals interaction and the large void space between different [SbSe] atomic chains of the Q1D structure. These defects produce a series of acceptor and donor levels in the band gap and make SbSe p-type under the Se-rich condition while n-type under the Se-poor condition. Five deep-level recombination-center defects are identified and their formation is difficult to be suppressed, imposing a serious limit to the development of high-efficiency SbSe solar cells. Our study demonstrates that the defects can be complicated and unconventional in the binary compound semiconductors with low symmetry and Q1D structures, which can be classified as chemically binary while structurally multinary.
This article was published in the following journal.
Name: ACS applied materials & interfaces
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