Trap States in p-NiO/n-Ga₂O₃ Heterojunctions on Czochralski β-Ga₂O₃ Crystals

Abstract

Heterojunctions (HJs) of p-NiO/n-Ga 2 O 3 were prepared by deposition of thin films of p-NiO by ion beam sputtering on bulk nominally undoped (100) oriented n-Ga 2 O 3 samples cleaved from Czochralski-grown (010) oriented crystal. Electrical properties and deep traps spectra were studied and compared with those obtained for similar samples with Ni Schottky diodes. Characteristic features of the NiO/Ga 2 O 3 HJs are the built-in voltage of over 2 V compared to 1 V in Ni Schottky diodes, a strong frequency dispersion of capacitance due to the presence of high density over 10 18 cm −3 of E c -0.16 eV traps in the thin region adjacent to the NiO/Ga 2 O 3 interface. For heterojunction diodes the strong increase of reverse current occurs at a much higher voltage than for Schottky diodes (120 V versus 60 V).