Silicon Donors at the GaAs(110) Surface: A First Principles Study
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- 作者：Zhijun Yi ; Yuchen Ma ; Michael Rohlfing
- 刊名：Journal of Physical Chemistry C
- 出版年：2011
- 出版时间：December 1, 2011
- 年：2011
- 卷：115
- 期：47
- 页码：23455-23462
- 全文大小：952K
- 年卷期：v.115,no.47(December 1, 2011)
- ISSN：1932-7455
文摘
Using the first principles ground state method, we systematically studied the DX center in bulk GaAs and GaAs(110). The DX center is found to be a metastable state in bulk GaAs and completely unstable in the top few layers of GaAs(110). We find that the charge states of SiGa defects on the GaAs(110) surface are localized, and the extra charge is mainly concentrated on the Si atom in the charged system. The localized extra charge of the defect on the surface affects the stability of the GaAs(110) surface. Our results show that the negative charging of SiGa would preferably occur at the surface, whereas the positively charged SiGa defect is unstable at the surface. Finally, our calculated STM images of clean GaAs(110) and charged Si:GaAs(110) using Tersoff鈥揌amann approximation [Tersoff, J.; Hamann, D. R. Phys. Rev. B1985, 31, 805鈥?13] are in good agreement with experimental results. Our results show that the charge state of defect at the surface has an important influence on the STM image. In addition, we show that the possible charge transfer process resulting from varying the bias voltage or the distance between tip and sample in the experiment can be easily understood based on the stability analysis of defect.