Annealing of electron irradiated, thick, ultrapure 4H SiC between 1100C and 1500C and measurements of lifetime and photoluminescence

Klahold, W. M.*; Devaty, R. P.*; Choyke, W. J.*; Kawahara, Kotaro*; Kimoto, Tsunenobu*; Oshima, Takeshi

Ultra-pure n-type (810 cm), 99 m thick epitaxial layers of hexagonal (4H) silicon carbide (SiC) were irradiated with electrons either at 170 keV with a fluence of 510 cm or at 1 MeV with a fluence of 110 cm in various geometries. Low temperature photoluminescence (LTPL) spectra and microwave photoconductance (PCD) lifetime measurements were carried out for all samples before and after annealing in argon in free standing mode or on a POCO carbon (Poco Graphite, Inc.) platform, every 50 C from 1100 C to 1500 C. However, no improvement in carrier lifetime was observed although previous studies reported that carbon diffused into SiC during high temperature treatment improves carrier lifetime. The result obtained in this study suggests that simple carbon diffusion model cannot be applied and more study is required to understand the injection of carbon interstitials into the SiC lattice.