Effect of Sacrificial AlN (Aluminum Nitride) Layer on the Deep Surface States of 4H-SiC

We investigated the effect of a sacrificial AlN layer on the deep energy level states of 4H-SiC surface. The samples with and without AlN layer have been annealed at 1300 °C for 30 minutes duration using a tube furnace. After annealing the samples, the changes of the carbon vacancy (V) related Z_1/2 defect characteristics were analyzed by deep level transient spectroscopy. The trap energy associated with double negative acceptor (V(2-/0)) appears at ˜0.7 eV and was reduced from ˜0.687 to ˜0.582 eV in the sacrificial AlN layer samples. In addition, the capture cross section was significantly improved from ˜2.1×10-14 to ˜3.8×10^-16 cm^-2 and the trap concentration was reduced by approximately 40 times.