Lattice Defects in Si_(1-x)Ge_x Devices by Proton Irradiation and their Effect on Device Performance

摘要

Results are presented of an extended study on the induced lattice defects and their effects on the electrical performance of n~+-Si/p~+-Si_(1-x)Ge_x/n-Si epitaxial diodes and heterojunction bipolar transistors (HBTs), subjected to a 20 and 86-MeV proton irradiation. The degradation of the electrical device performance increases with increasing proton fluence, while it decreases with increasing germanium content and proton energy. The induced lattice defects in the Si_(1-x)Ge_x epitaxial layers and the Si substrate are studied by DLTS. In the SI_(1-x)Ge_x diode epitaxial layers, electron capture levels associated with interstitial - substitutional boron complex are induced by irradiation, while two electron capture levels corresponding to the E-center and the divacancy are observed in teh collector region of the HBTs. The influence of the radiation source on device degradation is discussed taking into account the number of knock-on atoms and the nonionizing energy loss (NIEL). The radiation source dependence of performance degradation is attributed to the difference of mass and the probability of nuclear collision for the formation of lattice defects.