2Q'98 Report: Investigations of Ultra-High Vacuum Chemical Vapor Deposition of Silicon:Germanium Alloys On Silicon-On-Sapphire Substrates For Application to Device Fabrication Technology

The SiGe/SOS devices described in previous quarterly reports clearly show enhanced performance compared to control SOS devices which do not hace SiGe buried channels. However, significantly greater enhancements have been reported for n- and p-channel FETs having strained Si or Si_0.3Ge_0.7 active layers which are grown on a strain-relaxed Si_0.7Ge_0.3 buffer layer. To investigate whether such structures can be fabricated on sapphire substrates, we have begun work to grow a relaxed SiGe buffer layer on SOS substrates, thinned to about 10nm. Two UHV/CVD runs were done, growing a Si_0.72Ge_0.28 layer under different growth conditions on SOS wafers thinned to about 10nm. An analysis of these wafers is presented here.