Development of Si/SiGe Heterostructures
Final rept. Sep 87-Aug 90,
HUGHES RESEARCH LABS MALIBU CA
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We have developed new molecular beam epitaxy MBE materials growth and doping processes for the fabrication of SiSiGe heterostructure devices. We applied these new materials processes to the demonstration of cryogenic n-p-n SiSi 1-x GexSi heterojunction bipolar transistors HBT. This application has special significance as an enabling DoD technology for fast low noise, high performance readout and signal processing circuits for IR focal systems. We succeeded in developing reliable, versatile methods to grow very high quality SiSiGe strained layer heterostructures and multilayers. In connection with this program we developed methods to dope the Si and SiGe with B, Sb and Ga. B and Sb were found to be the preferred dopants for p and n regions respectively, of our HBT devices. Our test devices clearly displayed gain enhancement due to the heterojunction and provided useful gains from room temperature down to 10K.