Exponential Gain Degradation Behavior on Irradiated InP/InGaAs Double Heterojunction Bipolar Transistors

In this paper, the effects of 2 MeV-proton irradiation on the electrical characteristics of InP/InGaAs double heterojunction bipolar transistors (DHBTs) are investigated. The device characteristics suddenly degraded for proton fluences exceeding $1\times 10{^{{13}}}$ cm−2 and almost functionally failed for proton fluences reaches $1\times 10{^{{14}}}$ cm ${}^{-}2 $ . The increase in base current is directly responsible for the degradation of current gain. It was demonstrated that the reciprocal gain of irradiated InP/InGaAs DHBTs exhibits an exponential relationship with proton fluence over a broader fluence range below $5\times 10{^{{13}}}$ cm ${}^{-}2 $ , rather than a linear relationship as described by the Messenger-Spratt equation. The analysis of base current components and micro-Raman spectrums indicates that the electrostatic-potential modulation effect of irradiated defects as charged centers on the BE junction is the main cause of gain degradation. Furthermore, a comparison with irradiation effects of other bipolar transistors enhances our understanding of the varied impact of radiation-induced defects on the gain degradation across different transistor architectures.