GaAs/Si异质结的界面性质

本文应用普适参数紧束缚方法计算了GaAs/Si异质中界面组成、键能、自然键长、力常数以及键的弛豫等性质.由键能和力常数推断As和Ga原子均能在界面处与Si原子成键,但Si-As键更强一些,考虑到Si和Ga原子在界面的互扩散作用,提出了界面层的可能生长机理.作者认为界面层应由SiAs和GaSi组成的膺合金Ga_xA(?)_(1-x)Si构成,根据价带极大值随组分x的变化,指出x的范围处在0.1～0.6之间.由键的弛豫效应预示x的最佳范围在0.1～0.3之间.由此设想,通过控制组分,有可能使由晶格畸变产生的界面应力减至比较小,从而为消除因晶格畸变产生的应力缺陷给出了理论依据.

Study on Interface Properties of GaAs/Si Heterojunction

The interface properties of GaAs/Si heterojunction, including interface constituents, bond energies, natural bond length, force constante and relaxation effects of the bonds, have been calculated by using the universal parameter tight binding theory. It was concluded from bond energies and force constants that both As and Ga atoms can bond with Si atom, but Si-As bonding is stronger than Si-Ga bonding, Based on experimental results, it can be seen that both Ga and Si atoms have high inter-diffusion at GaAs/Si interface. A possible mechanism on GaAs/Si interfacial growth is proposed. Auther thinks that the thin interfacial layer is a mixed crystal, GaxAs1-xSi consisting of SiAs and GaSi. The 0.1-0.6 range of x value in obtained from valence band maximum EVBM varied with x and its optimum range of 0.1-0.3 on the basis of calculating relaxation effects of bonds is predicted. Therefore, the interface stress due to lattice distortion can be minimized by adjusting x during GaAs/Si growth. And it provides a theoretic base to eliminate or decrease the interface stress.