Improvement of AlSiO/GaN interface by a novel post deposition annealing using ultra high pressure

Abstract

In this study, a novel post-deposition annealing (PDA) technique employing ultra-high pressure was demonstrated for the first time. A 40 nm thick AlSiO gate insulator was deposited using atomic layer deposition (ALD) on n-type gallium nitride (GaN) epitaxial layers grown on free-standing GaN substrates. These PDA techniques were performed at 600 °C in a nitrogen ambient under 400 MPa, with normal pressure conditions used as the references. The annealing duration varied within the range of 10, 30, 60, and 120 min. For normal pressure annealing, the flat-band voltage of capacitance-voltage curves exhibited a shift towards the positive bias direction as the annealing time increased. Conversely, for the 400 MPa annealing, the flat-band voltage approached the ideal curve as the annealing time extended. For 400 MPa and 120 min, low interface state density of ∼5 × 1011 cm−2 eV−1 or less at E c −0.20 eV was obtained. These results suggest that post-deposition annealing under ultra-high pressure could be a viable method for improving the interfacial characteristics of AlSiO/GaN.