Zhao Zong-Yan, Yang Pei-Zhi
Faculty of Materials Science and Engineering, Key Laboratory of Advanced Materials of Yunnan Province, Kunming University of Science and Technology, Kunming 650093, People's Republic of China.
Phys Chem Chem Phys. 2014 Sep 7;16(33):17499-506. doi: 10.1039/c4cp01522c.
Using density functional theory calculations, the mechanism of insulator-to-metal transition of S-doped Si has been systematically investigated. The calculated crystal structure indicates that the gentle lattice distortion is caused by sulfur doping, and this doping effect is gradually weakened with the increase of sulfur concentration. Two distinct impurity energy levels in the band gap are induced by sulfur doping, and their position and width are linearly varying along with the increase of sulfur concentration. Owing to the overlap and dispersion of these impurity energy levels, the insulator-to-metal transition occurs at the sulfur concentration of 2.095 × 10(20) cm(-3), which is consistent with the experimental measurement. Moreover, the defect states related with sulfur doping show delocalization features and are more outstanding at the higher sulfur concentration. The calculated results suggest that S-hyperdoped Si is a suitable candidate for intermediate band solar cells.
通过密度泛函理论计算，系统地研究了硫掺杂硅从绝缘体到金属转变的机理。计算得到的晶体结构表明，硫掺杂导致了晶格的轻微畸变，且随着硫浓度的增加，这种掺杂效应逐渐减弱。硫掺杂在带隙中引入了两个不同的杂质能级，它们的位置和宽度随硫浓度的增加呈线性变化。由于这些杂质能级的重叠和弥散，在硫浓度为2.095×10(20) cm(-3)时发生了从绝缘体到金属的转变，这与实验测量结果一致。此外，与硫掺杂相关的缺陷态表现出离域特征，且在较高硫浓度下更为显著。计算结果表明，高硫掺杂硅是中间带太阳能电池的合适候选材料。
