Improved interfacial properties of thermal atomic layer deposited AlN on GaN

The interfacial properties of atomic layer deposited AlN on n-GaN substrate were investigated. Capacitance–voltage (C–V) characteristics showed that the sample with a 24 nm thick AlN had lower interface state density than the sample with a 7.4 nm thick AlN. Analysis on the X-ray photoelectron spectroscopy (XPS) spectra showed the better AlN formation near the AlN/GaN interface with a 24 nm thick AlN. The dominant peak shift to lower binding energy in the Al 2p core level spectra was observed with increasing the AlN thickness, which could be due to the strain relaxation resulted from the lattice mismatch between AlN and GaN.