The total-dose-effects of gamma and proton irradiations on high-voltage silicon-germanium heterojunction bipolar transistors

The total-dose-effects of gamma and proton irradiations on high-voltage silicon-germanium heterojunction bipolar transistors with the collector electrode elicited from the backside of the substrate are investigated. Pre- and post-radiation DC characteristics of the transistors are used to quantify the dose tolerance to the two different irradiation sources. Measurement results indicate that the devices exhibit a total dose tolerance up to Mrad level. The device response is indeed radiation source dependent and the proton irradiation can produce a more significant damage than the gamma irradiation, causing more pronounced performance degradation. The experimental results from both irradiations are compared and discussed in detail, and furthermore the underlying physical mechanisms are analyzed and investigated. The considerably different degradation behaviors are attributed to the extra displacement damage besides ionizing damage induced by the proton irradiation.