Electrical characteristics of atomic layer deposited AlN on n-InP

Atomic layer deposited AlN films on n-InP were electrically characterized. Compared to the sample without AlN, the interface state density obtained from the capacitance–voltage (C–V) measurements was found to decrease with a 7.4 nm thick AlN. According to X-ray photoelectron spectroscopy (XPS) measurements, the sample with a 0.7 nm thick AlN showed dominant peaks related with oxygen bonds (Al–O and In–O). For the sample with a 7.4 nm thick AlN, the dominant peak near the AlN/InP interface was associated with Al–O and N–In bonds whereas it was associated with Al–N bonds near the AlN surface. In addition, the strong emission peaks associated with Al–O bonds were observed across the AlN layer, which indicates that some part of AlN layer is composed of Al–O bonds (like Al₂O₃). The reverse leakage current for the sample with a 7.4 nm thick AlN at high electric field was explained by Poole–Frenkel (PF) emission, connected with nitrogen vacancy (V_N) and oxygen substituting for nitrogen (O_N) in the AlN layer.