论文部分内容阅读
在不同类型的部分缓解性SiGe缓冲层上生长了n型调制掺杂Si/SiGe异质结构,采用这一材料系统是为了得到足够大的导带突变。对样品进行了各种测试分析,如二次离子质谱,x光摆动像分析,透射电子显微镜分析,卢瑟福背散射分析和变温霍尔测量。在750℃生长的厚的线性渐变SiGe缓冲层样品中得到了最高的霍尔迁移率为1.5K下173000cm~2V~(-1)s~(-1)。这一层序达到的室温迁移率约为1800cm~2V~(-1)s~(-1)。发现不管是用没有Ge组分渐变的一般缓冲层,还是直接用有源层是调制掺杂SiGe势垒开始以缓解应变了的Si阱层,主要是在低温下霍尔迁移率严重地下降。
The n-type modulation doped Si / SiGe heterostructures were grown on different types of partially-ameliorating SiGe buffer layers using this material system in order to obtain a sufficiently large conduction band mutation. Samples were subjected to various test analyzes such as secondary ion mass spectrometry, x-ray oscillatory image analysis, transmission electron microscopy, Rutherford backscattering analysis, and variable temperature Hall measurements. The highest Hall mobility in the thick linear graded SiGe buffer layer grown at 750 ℃ is 173000cm ~ 2V ~ (-1) s ~ 1.5K at 1.5K. The room temperature mobility achieved in this sequence is about 1800cm ~ 2V ~ (-1) s ~ (-1). It has been found that the Hall mobility is reduced mainly by using a general buffer layer without graded Ge composition or by directly using the active layer to modulate the doped SiGe barrier to relieve strained Si well layers, primarily at low temperatures.