Negative-U system of carbon vacancy in 4H-SiC

Son, N. T.*; Trinh, X. T.*; Lvile, L. S.*; Svensson, B. G.*; Kawahara, Kotaro*; Suda, Jun*; Kimoto, Tsunenobu*; Umeda, Takahide*; Isoya, Junichi*; Makino, Takahiro; Oshima, Takeshi; Janzn, E.*

Nitrogen-doped n-type 4H-Silicon carbide (SiC) epitaxial layers were irradiated with electrons at 250 keV. Carbon vacancy (V) signals at both the h and k sites were studied using photoexitation Electron Paramagnetic Resonance (photo-EPR) and Deep Level Transient Spectroscopy (DLTS). As a result, double negative charge states of V, showing its negative-U system were revealed. By the direct correlation between EPR and DLTS data, it was concluded that Z is V at h site and Z is V at k site. In addition, we concluded that EH is a single donor level of V.