Limited reaction processing: Growth of Si1−Ge /Si for heterojunction bipolar transistor applications

Abstract

Abstract Limited reaction processing (LRP) of silicon-based materials is reviewed as an alternative growth method to molecular beam epitaxy (MBE). LRP is a chemical vapor deposition technique which uses wafer temperature, rather than gas flow switching, to initiate and terminate growth. Processing takes place within a cold-wall, quartz reaction chamber, and gases are changed between successive lamp-heated growth cycles. In addition to minimizing thermal exposure, the technique allows individual layers in a multi-layer structure to be deposited at their optimum growth temperature. LRP is particularly well suited to the growth and processing of metastable layers such as strained Si1−xGex on silicon. Several properties of LRP-grown Si1−xGex are shown to be similar to those reported for MBE material, including qualitative islanding behavior and quantitative measurement of the onset of misfit dislocation formation. However, a direct comparison of thermal stability reveals larger numbers of misfit dislocations in MBE-grown films upon annealing. The electrical behavior of misfit dislocations in heterojunction diodes, and the growth and analysis of high-quality Si/Si1−xGex/Si heterojunction bipolar transistors are also discussed.