Defect levels in high purity semi-insulating 4H-SiC studied by alpha particle induced charge transient spectroscopy

Iwamoto, Naoya; Onoda, Shinobu; Fujita, Natsuko   ; Makino, Takahiro; Oshima, Takeshi

We have studied defect levels in Schottky barrier diodes (SBDs) made of high purity semi-insulating 4H silicon carbide substrates by alpha particle induced charge transient spectroscopy. A shallow defect level with the activation energy around 0.3 eV is found in all SBDs annealed at temperatures from 1400 to 1600 C. Some other defect levels lying at deeper in the bandgap are found only in SBDs annealed at 1400 and 1500 C. We also found that the series resistance of SBDs decreases with increasing of annealing temperature. The decrease of series resistance seems to be corresponding to the removal of deep levels.