“…The activation energies of C, B, E and A are estimated to be (55 AE 5), (620 AE 30), (870 AE 30), (1200 AE 10) meV, respectively. The values of peaks A, B and C almost correspond to those obtained by PPA spectra in a previous paper [6]. However, in this study, the new peak E appears in the n-type sample, and this may be due to differences of crystal growth conditions such as a substrate temperature or VI/II ratio.…”