PROTON IRRADIATION EFFECTS ON THE PERFORMANCE OF SI1-XGEX DEVICES

Irradiation damage in n(+)-Si/p(+)-Si1-xGex/n-Si epitaxial diodes and heterojunction bipolar transistors (HBTs) by protons is studied as a f unction of germanium content, proton fluence and energy for the first time. The degradation of the electrical performance of devices increas es with increasing fluence: while it decreases with increasing germani um content and energy. The induced lattice defects in the Si1-xGex epi taxial layers and the Si substrate are studied by DLTS methods. In the Si1-xGex epitaxial layers for diodes, electron capture levels associa ted with interstitial-substitutional boron complex are induced by irra diation, while two electron capture levels corresponding to the E cent er and the divacancy are observed in the collector region of the HBTs. The influence of the radiation source on device degradation is then d iscussed taking into account the number of knock-on atoms and the noni onizing energy loss (NIEL). The radiation source dependence of perform ance degradation is attributed to the difference of mass and the proba bility of nuclear collision for the formation of lattice defects.