Radiation source dependence of degradation and recovery of irradiated Si1-xGex epitaxial devices

The degradation and recovery of irradiated n⁺-Si/p⁺-Si_1-xGe_x epitaxial diodes and n⁺-Si/p⁺-Si_1-xGe_x/n-Si epitaxial heterojunction bipolar transistors (HBTs) are studied as a function of fluence and germanium content. The degradation of electrical performance of the devices increases with increasing fluence, while it decreases with increasing germanium content. In the Si_1-xGe _x epitaxial layer of devices, an electron capture level which is associated with interstitial boron, is induced. The impact of radiation source on the degradation of performance is correlated with simulations of numbers of knock-on atoms and the nonionizing energy loss. From the experiment of isochronal thermal annealing, it is concluded that the electron capture levels are mainly responsible for the degradation of electrical performance