Investigation of fast and slow traps in atomic layer deposited AlN on 4H-SiC

We investigated the electrical and interfacial properties of AlN/4H-SiC interfaces prepared by atomic layer deposition (ALD). The conductance–voltage (G/ω–V)characteristics were identified based on two types of traps: fast and slow. Fast traps located in the semiconductor energy gap close to the AlN/SiC interface showed both narrow and wide energy distributions. Slow traps with defects in the AlN layer exhibited a narrow energy distribution. According to X-ray photoelectron spectroscopy analysis, the formation of AlN during the initial ALD deposition was unclear and some of the oxygen atoms present on the SiC surface were converted into Al₂O₃. Both O 1s and Al 2p core level spectra shifted to lower energies as the AlN thickness increased. This was associated with the strain relaxation originating from the lattice mismatch between AlN and SiC.