Metamorphic InP/InGaAs double-heterojunction bipolar transistors on GaAs grown by molecular-beam epitaxy

Abstract

InP/InGaAs double-heterojunction bipolar transistor (HBT) structures were grown metamorphically on GaAs substrates by solid-source molecular-beam epitaxy. A linearly graded ${\mathrm{In}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{P}$ (x varying from 0.48 to 1) buffer layer was used to accommodate the strain relaxation. The crystallinity of the buffer layer and the HBT structure was examined by x-ray diffractometry. Devices with $\text{5×5\hspace{0.05em}μ}{\mathrm{m}}^{\mathrm{2}}$ emitter area showed a typical peak current gain of 40, a common-emitter breakdown voltage $({\mathrm{BV}}_{\mathrm{CEO}})$ higher than 9 V, a current gain cut-off frequency ${\mathrm{(f}}_T)$ of 46 GHz, and a maximum oscillation frequency ${\mathrm{(f}}_{\max })$ of 40 GHz.