红外光电子材料碲镉汞异质外延结构理论研究

文章介绍了基于第一性原理的LAPW方法就Hg空位缺陷对碲镉汞材料的电子结构的影响进行了研究。首先选择Hg0. 5 Cd0. 5 Te体系详细分析了Hg空位引起的弛豫,包含Hg空位缺陷体系的电荷密度、成键电荷密度和态密度,得到了碲镉汞材料形成Hg空位情况下的空位第一近邻阴离子悬挂键重整的形式以及Hg空位所形成的双受主能级。计算发现了Hg空位引起第一近邻Te原子5s态能级向高能端移动的现象。 同时,对实验中通常利用As钝化基底表面来有效地控制外延生长的极性进行了研究。本文也介绍了基于密度泛函理论模拟了单个及多个As原子在Si (211)重构表面上的吸附、置换行为,通过系统地计算各种可能的吸附、置换构型,并进一步分析能量、键长等性质,对As在Si(211)表面的钝化机理进行了初步研究探讨。对Cd、Te在As钝化前后Si (211)表面上的吸附行为也进行了研究分析,为外延生长实验中利用As钝化来保证B 面极性的做法提供了一定的理论依据。

The Theoretical Study of the Hetero-epitaxial Growth for the Infrared Optoelectronic Material HgCdTe

The first princip lemethods is used to study the effects of the most important defects and impurities on the properties of the HgCdTematerials. The relaxation calculations indicate that the nearest neighbor Te around the Hg vacancy defect contract toward to the defect site. The contract relaxation is attributed to the concentration of the electrons around the defect site accompanying the dangling bond reconstruction. From calculated results ofDOS, it is found that the Hg vacancy defect produces double accep tors. Meanwhile,we have found that the energy of 5 s state of the nearest neighbor Te shift up as the dangling bond reconstruction. At the same time, the adsorp tion and replacement behaviors of arsenic on the reconstructed Si (211) surface have been simulated by the DFT. By calculating several possible structures as well as analyzing the energies and bond lengths, the passivation of the arsenic on the Si surface is studied. Then, the adsorp tion behaviors of tellurium and cad- mium on the clean and As - passivated Si (211) surface are investigated. The simulation results have some important roles in the growth of Si (211) surface passivated by As. Key words:HgCdTe; Hg vacancy; The first princip le methods; Si reconstructed surface; As passivation; adsorp tion of cadmium; adsorp tion of tellurium