Improved conduction in GaN Schottky junctions with HfO2 passivation layers through post-deposition annealing

Abstract

The conduction in GaN Schottky junctions with HfO2 passivation layers can be improved by post-deposition annealing (PDA). Surface defects and ionic states of Ga-polar GaN removed by PDA lead to the formation of downward bend banding with a positive surface polarity. X-ray photoelectron spectroscopy is utilized to assess the effects of PDA on the atomic composition and surface polarity changes at the HfO2/GaN interface and GaN surface. The leakage current level and ideality factor of the GaN Schottky junctions improved from 4.73 x 10(-6) A cm(-2) to 8.21 x 10(-8) A cm(-2) and from 1.47 to 1.14, respectively. With the application of PDA, the flow of leakage current through the Schottky metal area reduced as the surface defect states were removed. (c) 2020 The Japan Society of Applied Physics