Thermally stimulated luminescence in full-size 4H-SiC wafers

We performed non-contact and non-destructive spatially resolved characterization of traps and recombination centres in two-inch-diameter p-type 4H-SiC wafers using thermally stimulated luminescence (TSL) and scanning room temperature photoluminescence (PL). The TSL glow-curve maximum is located at about 190 K for the Al-doped wafers and the TSL spectrum has a maximum at 1.8 eV, which coincides with the spectrum of the 'red' PL band in the same crystal. The TSL intensity exhibits a noticeable inhomogeneity across the wafers. The spatial distribution shows a negative contrast compared to PL maps, indicating a variation of concentration of the TSL centres across the wafer. The origin of the centres is discussed.