Electron Irradiation Induced Vacancy Defects Detected by Positron Annihilation in 6H-SiC

摘要

This paper presents positron lifetime results which give information on the nature of vacancy defects induced by electron irradiation in bulk nitrogen doped (n_D-n_A= 2.3x10~(17) cm~(-3)) Cree 6H-SiC. The electron irradiations have been performed at different energies and with different fluences from 5x10~(17) e~-cm~(-2) to 3x10~(18) e~-cm~(-2). Positron lifetime have been measured with a ~(22)NaCl source as a function of temperature between 15 and 300 K. The lifetime spectra were analyzed as sums of two exponential lifetime components τ_i weighted by the intensities I_i, convoluted with the resolution function. From the temperature dependence of the lifetime spectra we can infer that several vacancy defects exist in the electron irradiated n-type 6H-SiC. The nature of detected vacancy defects depends on the electron energy.