Aluminium nitride deposition on 4H-SiC by means of physical vapour deposition

190 nm thick aluminium nitride (AlN) with a dielectric constant of 8.8 was deposited by physical vapour deposition (PVD) on n- and p-type Si and n-type 4H-SiC samples. The Metal–Insulator–Semiconductor, MIS, structures were analysed by IV and CV techniques and 1.2 kV SiC diodes were used to evaluate leakage current before and after AlN deposition. The samples were prepared both with and without 5% HF dip after UV exposure, prior to the AlN deposition. Structural AlN analysis showed polycrystalline composition with a dominant [002] phase, a density of 3.27 g/cm3 and stochiometry of Al0.4N0.6. Surface pre-treatment did not have much influence on the IV characteristics of Si samples (breakdown field ∼3 MV/cm). However, the non-HF-etched sample is characterised by 2.5 times smaller CV hysteresis for the p-type sample at 100 kHz. The SiC MIS structures have a high leakage current, nevertheless a beneficial influence of UV irradiation is observed in the case of the non-HF-etched sample (soft breakdown field ∼3 MV/cm compared to ∼2 MV/cm for HF-etched sample). The diode reverse current was about 2 pA before UV irradiation and 4 and 600 pA after AlN deposition at room temperature and at 150 °C, respectively.