Response of epitaxial layer of 4H-SiC to β-rays and X-rays irradiation

Abstract

4H-SiC is one of the most promising indirect wide-bandgap (3.3 eV) semiconductor for power devices used in the emerging area of high-voltage and high-temperature electronics as well as space and radiation harsh environments applications. In this work some complementary techniques (micro-Raman, absorption, steady-state and time resolved photoluminescence spectroscopy) have been used to study the properties of epitaxial layer (12μm) of 4H-SiC and to explore the effects of ionizing radiation on it by using β-rays and two different X-rays sources. The dose range spanned from 1 kGy up to 100 kGy for electrons (2.5 MeV), 16 kGy for the first X-rays source (X-ray tube W target operating at anode bias voltage 28 kV) and 100 kGy for the second X-rays source (X-ray tube W target operating at anode bias voltage 100 kV). In the samples irradiated with electron beam the lifetime of the excitonic band decreases when the deposited dose increases. In particular, in the samples with higher native defectiveness (extended or point defects) the effect starts from lower deposited doses. Conversely, in the samples irradiated with X-rays (both sources) there aren’t effects at the same deposited dose as β-rays. These findings suggest that irradiation with electrons induces defects related to atomic displacement. Finally, the effects of thermal treatments in air, from 100°C up to 900°C, have been explored to study the recovery properties of 4H-SiC.