组份线性渐变SiGe缓冲层的生长及其表征

Growth and Characterization of Linearly Graded SiGe Buffer\+*

采用阶跃式 Ge H4 流量增加和温度降低的方法 ,在超高真空化学气相淀积系统中生长了线性渐变组份的 Si Ge缓冲层 ,并在其上生长出了驰豫的 Si0 .6 8Ge0 .32 外延层 .俄歇电子能谱证实缓冲层 Ge组份呈线性渐变 .Raman散射谱得出上表层应变驰豫度为 32 % ,与 X射线双晶衍射结果符合得很好 .腐蚀的样品观察到沿两个〈1 1 0〉方向规律性分布、大小和螺旋走向完全一致的位错团密度约为 5× 1 0 7/cm2 .

With the technique that the flux of germane (GeH\-4) increases while the growth temperature decreases with the step change,a sample consisting of a linearly graded SiGe buffer layer and a uniform relaxed Si 0.68 Ge 0.32 layer was grown by ultrahigh vacuum chemical vapor deposition system.The linear change of Ge content was tested by auger electron spectrum.The relaxation ratio of the strain in the topmost SiGe layer is calculated to be about 32% from the Raman shift difference in Si\|Si vibration modes between Si 0.68 Ge 0.32 epilayer and Si substrate,as is in agreement with the result of double\|crystal X\|ray diffraction.The sample having been etched,dislocation pile\|ups are observed to distribute along 〈110〉 regularly with a uniform size and same screw\|direction,whose density was about 5×10 7/cm 2.The reason for the generation of dislocation pile\|ups was discussed.