Base-emitter injection characterization in low-temperature pseudo-heterojunction bipolar transistors

Carrier injection characteristics in a pseudo-heterojunction bipolar transistor (pseudo-HBT) are clarified both theoretically and experimentally. It is found that a low-concentration external-base structure completely rejects carrier injections and selectively injects electrons into the intrinsic base at low temperatures. This unique property inherent in low-temperature operation is verified in an experimental pseudo-HBT. Based on the results, the vertical and horizontal scaling rules for pseudo-HBTs are clarified. The analysis reveals that the low-temperature bipolar transistor has a very small emitter- and external-base charging time, which allows excellent vertical and horizontal scalability for superior to that of conventional room-temperature transistors