Correlation between direct characteristic deficiencies and deep levels in 6H–SiC Schottky diodes

Excess current at low forward bias is observed for large area Ni Schottky diodes on n- and p-type 6H SiC. Random telegraph signal (RTS) measurements, carried out on these defective devices, show discrete time switching of the current. The traps signatures (Ea=0.35 eV, σ=1.17×10−18 cm2 for the n-type, Ea=0.43 eV, σ=1.8×10−20 cm2 for the p-type) extracted from DLTS measurement are very close to the one obtained from RTS. This strong correlation between the two different technique is attributed to the presence of an extended defect which presents different charge states (i.e. an extended defect decorated by punctual traps). This assumption is enforced by the DLTS measurements as a function of the filling time and as a function of the field.