Diffusion length and junction spectroscopy analysis of low-temperature annealing of electron irradiation-induced deep levels in 4H-SiC

摘要

The effects of low-temperature annealing in 8.2 MeV electron-irradiated 4H-SiC Schottky diodes were investigated. Deep-level transient spectroscopy and minority-carrier diffusion length (L_d) measurements were carried out on not-irradiated samples and on irradiated samples before and after thermal treatments up to T = 450℃. We found that several deep levels in the upper half band gap (S1 with enthalpy E_T=0.27 eV, S2 with E_T=0.35 eV, S4 with E_T= 0.71 eV, and S5 with E_T =0.96 eV) anneal out or modify at temperature values lower or equal to T = 450℃, whereby their progressive annealing out is accompanied by a net increase of L_d, up to 50% of the value in the as-irradiated sample. We drew some conclusions regarding the microscopic nature of the defects related to the deep levels, according to their annealing behavior.