Band alignment of HfO2/Al0.25Ga0.75N determined by x-ray photoelectron spectroscopy: Effect of SiH4 surface treatment

The band-alignment of atomic layer deposited (ALD)-HfO2/Al0.25Ga0.75N was studied by high resolution x-ray photoelectron spectroscopy measurements for both the non-passivated and SiH4 passivated AlGaN surfaces. The valence band offset and the conduction band offset for the ALD-HfO2/Al0.25Ga0.75N interface were found to be 0.43 eV and 1.47 eV, respectively, for the non-passivated sample, and 0.59 eV and 1.31 eV, respectively, for the SiH4-passivated sample. The difference in the band alignment is dominated by the band bending or band shift in the AlGaN substrate as a result of the different interlayers formed by the two surface preparations.