SI SI1-XGEX DOTS GROWN BY SELECTIVE EPITAXY

Using low-pressure chemical vapour deposition, single-layer SiGe and s ingle-quantum-well (SQW) Si/SiGe dots were deposited by selective epit axy in SiO2 windows using a SiCl2H2/GeH2/H2-based chemistry. The unifo rmity of selective deposition was investigated over a range of pads fr om 300 mum down to 0.14 mum. No change of growth rate and Ge fraction in SiGe was observed for patterns down to 2 mum. Only for 0.18 mum wid e dots was a slight increase in Si height measured as compared with th e unpatterned area. However, the SiGe layer in the SQW dots was 3-4 ti mes thicker, which could be due to islands or to an enhanced growth of SiGe in the small openings. Arrays with hundreds of millions of 0.15 mum single-quantum-well Si/SiGe dots very uniform in height could be d eposited.