Heterojunction bipolar transistor and base-collector grade layer

Abstract

A heterojunction bipolar transistor and a base-collector grade layer. The heterojunction bipolar transistor includes a substrate, a sub-collector layer, a collector layer, a base layer, a base-collector grade layer and an emitter layer. The sub-collector layer is disposed on the substrate. The collector layer is disposed over the sub-collector layer. The base layer is disposed over the collector layer. The base-collector grade layer is disposed between the base layer and the collector layer, and includes at least two stacked periodic structures. Each periodic structure includes an In0.53Ga0.47As layer and an AlxGayIn1-x-yAs layer stacked on the In0.53Ga0.47As layer. The range of x is 0.04~0.44, the range of y is 0.44~0.04, and the thickness of the AlxGayIn1-x-yAs layer is 0.6 nm~1.8 nm. The emitter layer is disposed on the base layer.

Dependencies are inferred from the claim text.