DAMAGE CORRELATIONS IN SEMICONDUCTORS EXPOSED TO GAMMA-RADIATION, ELECTRON-RADIATION AND PROTON-RADIATION

The use of nonionizing energy loss (NIEL) in predicting the effect of gamma, electron and proton irradiations on Si, GaAs and InP devices is discussed. The NIEL for electrons and protons has been calculated fro m the displacement threshold to 200 MeV. Convoluting the electron NIEL with the ''slowed down'' Compton secondary electron spectrum gives an effective NIEL for Co-60 gammas, enabling gamma-induced displacement damage to be correlated with particle results. The fluences of 1 MeV e lectrons equivalent to irradiation with 1 Mrad(Si) for Si, GaAs and In P are given. Analytic proton NIEL calculations and results derived fro m the Monte Carlo code TRIM agree exactly so long as straggling is not significant. The NIEL calculations are compared with experimental pro ton and electron damage coefficients using solar cells as examples. A linear relationship is found between the NIEL and proton damage coeffi cients for Si, GaAs and InP devices. For electrons, there appears to b e a linear dependence for n-Si and n-GaAs, but for p-Si there is a qua dratic relationship which decreases the damage coefficient at 1 MeV by a factor of similar to 10 below the value for n-Si. The present resul ts greatly extend the range of environments for which damage calculati ons based on NIEL can be applied. The NIEL results are presented in ta bular form for ease of calculation.