InGaAs/InP double-heterojunction bipolar transistors with step graded InGaAsP between InGaAs base and InP collector grown by metalorganic chemical vapor deposition

Abstract

We have fabricated InGaAs/InP double-heterojunction bipolar transistors (DHBTs) grown by metalorganic chemical vapor deposition (MOCVD). By inserting step graded InGaAsP layers between p+-InGaAs base and n−-InP collector, the current gain of DHBTs with the graded layers was about twice as large as that without the graded layers, and the dependence of collector current on collector/emitter voltage was smaller than that without graded layers. The current gain was measured up to 2300 with 25×25 μm2 emitter area at a collector current density of 1×104 A/cm2.