Bipolar junction transistors fabricated in silicon-on-sapphire

Abstract

The effects of processing temperature on collector leakage current in bipolar junction transistors (BJTs) fabricated in silicon-on-sapphire (SOS) were examined. At low process temperatures (850°C a reduction of five orders of magnitude in the collector leakage current was observed. Excellent I–V characteristics were obtained on both NPN and PNP transistors fabricated at lower temperatures. Measured DC current gain β for the NPN devices was 30, and that of the PNP devices was 40. Additionally, current mode logic (CML) circuits fabricated using these transistors exhibited well behaved DC switching characteristics.