Effects Of Annealing On The Interfacial Properties And Energy-Band Alignment Of Aln Dielectric On 4h-Sic

Interfacial properties and energy-band alignment of annealed AlN dielectric films on Si-face 4 degrees off-axis 4H-SiC substrates were characterized and demonstrated by x-ray photoelectron spectroscopy (XPS) and current-electric field (I-E) measurements. The XPS results reveal that the Al-O bonds and the silicon suboxides can convert into more stable Al-N bonds and Al-O-Si bonds at the AlN/4H-SiC interface under 1000 degrees C annealing. The variations in both oxygen-rich composition and the crystallinity in AlN make annealing-dependent conduction band offsets of as-deposited and annealed AlN/4H-SiC to be 1.36eV and 1.20eV, respectively. Meanwhile, I-E measurements separately yield the occurrence of the Fowler-Nordheim (FN) tunneling and space-charge-limited conduction in as-deposited and annealed metal-insulator-semiconductor capacitors, corresponding to lower barrier heights of 0.92eV and 0.54eV, respectively. The reason for the energy-band shift between I-E derivations and the XPS results was analyzed and demonstrated together. These results can provide considerable insight into the energy-band alignment of AlN as gate dielectric or passivation layers on 4H-SiC based devices.