Unintentionally doped 4H-SiC homoepitaxial layers, grown by hot-wall chemical vapour deposition, were studied using photoluminescence techniques at 10 to 240K. A broadband green luminescence was observed. Carbon vacancies were revealed by electron spin resonance at 110K. The results strongly suggested that the green band luminescence, as shallow donor-deep accepter emission, was attributed to the C vacancies and extended defects. The broadband green luminescence spectrum could be fitted by a two Gauss-type spectra using non-linear optimization techniques. This showed that the broadband green luminescence originated from the combination of two independent radiative transitions. The centers of two energy levels were located 2.378 and 2.130eV below the conduction band, respectively, and the ends of two energy levels were expanded and superposed each other.

Deep Level Defects in Unintentionally Doped 4H-SiC Homoepitaxial Layer. R.Jia, Y.Zhang, Y.Zhang, Y.Wang, L.Zhang: Journal of Semiconductors, 2009, 30[3], 033003