Bipolar transistor

Abstract

The present invention relates to a hetero-bipolar transistor. This transistor comprises a semi-insulating InP substrate, a buffer layer on the substrate, a sub-collector layer on the buffer layer, a collector layer on the sub-collector layer, a base layer on the collector layer, a wide-gap emitter layer on the base layer and a emitter contact layer on the emitter layer. The emitter layer extends the emitter contact layer, so the edge of the emitter layer is apart from the emitter contact layer and entirely covers the region where the collector layer and the sub-collector layer are overlapped to each other. According to this configuration, the transistor shows the enhanced reliability and the improved high frequency performance.

Dependencies are inferred from the claim text.