Influence of Annealing, Oxidation and Doping on Conduction-Band near Interface Traps in 4H-SiC Characterized by Low Temperature Conductance Measurements

Abstract

Current power MOSFET devices on Silicon Carbide show a limited inversion channel mobility, which can be a result of the expected very high density of interface states near the conduction band . In the current work, the effect of the post implantation annealing temperature, the thermal oxidation and the nitrogen doping of the n-epi layer on the density of these interface traps is investigated using capacity-conductance measurements. Instead of the usage of very high frequencies as used in , in this investigation the measurements were performed in liquid nitrogen to decrease the recharging times of the interface traps.Due to the different processing the samples showed a wide spreading of the inversion channel mobility. The conductance measurements show a characteristic peak caused by the conduction band near interface traps especially for the low temperature measurements. But these traps could not be correlated to the mobility. Instead, a correlation to the nitrogen doping of the epi layer could be observed.