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In_xGa_(1-x)As/Ga As之间晶格失配度与X成线性关系,其最大值为7％。因而当外延层厚度大于临界厚度时在界面会产生微缺陷,这些缺陷对其材料性能有很大影响。因此对In x Ga_(1-x)As Ga As界面研究就显得很重要。本工作就GaAs衬底上MBE生长In_(0.2)Ga_(0.8)As/Ga As超晶格样品进行平面,断面的TEM研究。实验结果表明超晶格平整,均匀,只看到位错一种微缺陷。GaAs衬底内位错。表面机械损伤会在超晶格层内引入位错。在In Ga As Ga As界面上失配位错情况如图1所示。图1a为[110]方向衬象,可见界面上位错线及露头(箭头所示)倾转约30,在图1b中看到位错网络,箭头所示位错为1a中所示的露头。
The lattice mismatch between In_xGa_ (1-x) As / GaAs is linear with X, with a maximum of 7%. Therefore, when the thickness of the epitaxial layer is greater than the critical thickness, micro-defects are generated in the interface, and these defects have a great influence on the material properties. Therefore, it is very important to study the In x Ga 1-x As Ga As interface. In this work, the TEM and TEM studies of MBE grown In_ (0.2) Ga_ (0.8) As / Ga As superlattice samples on GaAs substrates were carried out. The experimental results show that the superlattice is flat and uniform, and only one micro-defect of dislocation is seen. Dislocation in GaAs Substrate. Surface mechanical damage introduces dislocations in the superlattice layer. Misfit dislocations at the In Ga As GaAs interface are shown in Figure 1. Figure 1a shows the [110] directionally lined figure. It can be seen that the dislocation lines and outcrops (indicated by arrows) in the interface tilt about 30 and the dislocation network is seen in Figure 1b. The dislocations indicated by the arrows are the outcrops shown in 1a.