RF characteristics of proton radiated large-area SiGe HBTs at extreme temperatures

Abstract

The radio frequency (RF) characteristics of proton irradiated large-area silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs) at extreme temperatures (liquid nitrogen temperature of 77K and high temperature of ∼430K) are reported in this work. Large emitter area high-power SiGe HBTs fabricated in a commercial BiCMOS process were irradiated with proton, at various fluences from 1×1012p/cm2 to 5×1013p/cm2. Small-signal ac experimental characterizations were achieved for pre- and post-radiation devices at room temperature, cryogenic and high temperatures. We show that proton radiated large-area SiGe HBTs are naturally suitable for electronic operations at extreme temperatures. Investigation of proton radiation on large-area SiGe HBTs at liquid nitrogen temperature (77K) demonstrates great potential of SiGe power HBTs for space applications. Moreover, performance of proton radiated SiGe power HBTs at high temperature of ∼430K indicates a better tolerance of proton radiation than room temperature. Possible underlying mechanisms for the improvement of radiation robustness at cryogenic and high temperatures are discussed. The results demonstrate the possibility of using large-area SiGe HBTs in power amplification for wireless applications under severe radiation and extreme temperature environment without any intentional radiation hardening.