High speed InGaP/GaAs HBTs with fmax of 159 GHz

Abstract

InGaP/GaAs heterojunction bipolar transistors (HBTs) with a heavily-doped and thin base layer are described. Low base leakage current of 2.3 × 10 −7A μm −1 at the emitter-base periphery was obtained, and excellent high-frequency performances of a cut-off frequency f T of 115 GHz and a maximum oscillation frequency f max of 159 GHz were achieved by using a 30 nm-thick base layer doped to 1 × 10 20cm −3, which is the first report of both parameters being over 100 GHz in an InGaP/GaAs HBT. Delay time component analysis exhibited that the intrinsic transit time was reduced by 0.4 ps by reducing the base thickness from 50 to 30 nm.