Self-aligned InP/InGaAs heterojunction bipolar transistor and It's monolithic integration with p-i-n photodiode

Abstract

In this thesis, high-speed InP/InGaAs HBTs with the crystallographically defined emitter contact were fabricated and their performances were characterized. The consistent and desired undercut profile was reproducibly achieved by the crystallographically defined shape of the emitter contact and adjustment of the thickness of the InP dummy emitter layer. InP/InGaAs HBTs demonstrated good current-voltage characteristics, having low offset voltage of 64 mV, low knee voltage less than 0.5 V, and high current gain of 50. High-frequency characteristics of $f_T = 94 GHz$ and $f_{max}$ = 124 GHz and the power performances with power density of $1.41 mW/μm^2$ and gain of 13.05 dB at 10 GHz were obtained from the fabricated devices with a $1 x 20 μm^2$ emitter area. These results indicate that newly developed InP/InGaAs HBTs are promising for fabricating submicron emitter size HBT and obtaining high-frequency characteristics and high microwave power performances. New self-alignment technologies employing InGaAs CDC technology are successfully developed for high-speed InP/InGaAs HBTs. InGaAs CDC technology utilizes the anisotropic etching characteristics of InGaAs. The fabricated InP/InGaAs HBTs with a $1 x 20 μm^2$ emitter area exhibited frequency $f_T = 112$ GHZ and $f_{max} = 307 GHZ. The good overall performance of the fabricated HBTs demonstrates the effectiveness of the new CDC technology, characterized by reproducible self-alignment of the emitter and base contacts with the damage-free etched surface. Newly developed CDC technology is promising for fabricating the self-aligned submicron emitter InP/InGaAs HBT and obtaining high-speed performance characteristics for IC applications. The monolithically integrated InP-based HBT and p-i-n photodiode using stack-shared layer scheme have been proposed and the photodiode with new structure has been successfully demonstrated. The 20-μm-diameter device exhibited a dark current of 1.5 nA under 3 V reverse bias, with a...