GaAs(001)衬底上经双缓冲层生长的Hg_(1-x)Cd_xTe-HgTe超晶格结构

用 X-射线衍射测定了分子束外延 ( MBE)法生长的 Hg1-x Cdx Te- Hg Te超晶格样品在 ( 0 0 1 )附近的扫描徊摆曲线 ,并用动力学理论模拟计算出衍射曲线 ,实验曲线与理论计算基本上相符合 .由实验衍射曲线计算出的超晶格周期长度 ,阱 Hg Te层厚度及垒 Hg1-x Cdx Te层厚度与模拟计算的相一致 .用透射电子显微镜 ( TEM)对同一样品的横截面进行了分析 ,对 Cd Te/Zn Te/Ga As异质结界面失配位错的组态特征进行了研究 .证明用 Cd Te/Zn Te作为双缓冲层比单一的 Cd Te有较好的效果 .截面 TEM高分辨率明场象显示 Hg1-x Cdx Te- Hg Te超晶格的生长较为成功 ,界面较为平整 .由截面 TEM高分辨率明场象观测的周期长度与 X-射线衍射测定的结果相接近

Structure of Hg_(1-x) Cd_xTe-HgTe Superlattice Grown Through Bibuffer Layers on GaAs Substrate

A rocking curve of Hg 1 x Cd x Te HgTe superlattice sample grown by molecular beam epitaxy (MBE) was determined by X ray diffraction (XRD)around the (001) crystallographic plane. It shows primarily the superlattice structure property. A simulation curve was calculated from the dynamic theory. There is a good agreement between the two curves, and the Hg 1 x Cd x Te HgTe superlattice period length, HgTe well thickness, and Hg 1 x Cd x Te barrier thickness measured from the experimental curve are consistent with what calculated from the simulation curve. The CdTe/ZnTe double buffer layers were employed instead of the CdTe single buffer layer. The micrographs of cross sections of the Hg 1 x Cd x Te HgTe superlattice and the heterojunctions between the bibuffer layers and GaAs substrate were demonstrated by transmission electron microscopy (TEM), and the feature and distribution of mismatch dislocation at the CdTe/ZnTe/GaAs heterojunctions were also analyzed. It is clearly shown that the CdTe/ZnTe double buffer layers are more effective than the single CdTe buffer layer for some defects. The high resolution bright field micrograph of the superlattice cross section shows that the smoothness of the interface, as well as that the average superlattice period length is similar to one from X ray diffraction.