GaAs/In0.08Ga0.92As Double Heterojunction Bipolar Transistors with a Lattice-Mismatched Base

Abstract

The critical layer thickness for misfit dislocation generation in a GaAs/InGas/GaAs DH structure is investigated experimentally. Introduction of compositionally graded layers with 300 Å thickness into hetero-interfaces is found to increase the critical layer thickness for misfit dislocation generation about three-fold. An optimum growth temperature of about 510°C is obtained by measuring the photoluminescence intensity of the DH structure. Using these results, a GaAs/In_0.08Ga_0.92As heterojunction bipolar transistor with a lattice mismatched InGaAs base is fabricated for the first time. The current gain of 20 is achieved at a collector current density of 2×10⁴ A/cm².