The high-speed performance of [formula omitted] Schottky collector HBTs

Abstract

We investigated the high-speed performance of Si 1−x Ge x/ CoSi 2 Schottky collector heterojunction bipolar transistors (SCHBTs). The fact that a Si/Si 1−x Ge x/ CoSi 2 SCHBT can suppress the base push out and eliminate the collector charging time, which is a delay component that makes a sizable contribution in high-speed heterojunction bipolar transistors (HBTs), makes it possible to obtain very high and current-stable speeds with this structure. Analysis of the different delay components contributing to the emitter-to-collector delay time shows that for Schottky collector transistors with a base thickness of 300 Å or less, the structure should be optimized to minimize the emitter delay time even at high collector current densities in order to further improve the speed. An advantage is the lower power consumption when this SCHBT is compared with conventional HBTs.