Thermal stability of defects centers in n- and p-type 4H-SiC epilayers generated by irradiation with high-energy electrons

Reshanov, S. A.*; Beljakowa, S.*; Zippelius, B.*; Pensl, G.*; Danno, Katsunori*; Alfieri, G.*; Kimoto, Tsunenobu*; Onoda, Shinobu; Oshima, Takeshi; Yan, F.*; Devaty, R. P.*; Choyke, W. J.*

n- and p-type 4H-SiC epilayers were irradiated with electrons at 170 keV or 1 MeV. Subsequent annealing (in Ar, 30 min) up to 1700 C was carried out. Defects in the samples were investigated using DLTS (Deep Level Transient Spectroscopy). As a results, for n-type, dominant defects were Z1/Z2 and EH7, and they can observed for both 170 keV- and 1 MeV-irradiated samples. Both defects decreased with increasing temperature up to 1100 C, although they appeared again at 1400 C. Then they disappeared at 1600 C. For p-type, defects named UK1 and HK2 were observed and they were very stable. No significant decrease was observed after 1700 C annealing.