Two-dimensional hole gas formation at the kappa-Ga2O3/AlN heterojunction interface

Typically, semiconducting oxides and nitrides exhibit strong conductivity type asymmetries. In this work, we observed and interpreted the emergence of p-type conductivity at the kappa-Ga2O3/AlN interface. Films of lightly Sn-doped-Ga2O3 were deposited by Halide Vapor Phase Epitaxy (HVPE) on AlN/Si templates. Capacitance-voltage (C-V), current-voltage (I-V) measurements on Ni Schottky diodes and Ti/Au Ohmic contacts deposited on the layer surface unexpectedly showed p-type-like behavior, while Electron Beam Induced Current (EBIC) images collected with different beam energies suggest that the EBIC collection occurs near the Ga2O3/AlN interface, which also implies the formation of a p-type layer at this interface. We modelled this effect, taking into account the difference in spontaneous electrical polarization of kappa-Ga2O3 and AlN and this indicated a layer of two-dimensional holes can form at this interface. The possibility to detect this layer depends on the balance between the doping level and the thickness of the kappa-Ga2O3. O2022 Elsevier B.V. All rights reserved.

Automated summary

Typically, semiconducting oxides and nitrides exhibit conductivity type asymmetries. In this study, p-type conductivity was observed at the kappa-Ga2O3/AlN interface. Lightly Sn-doped-Ga2O3 films were deposited on AlN/Si templates using HVPE method. Measurements on Schottky diodes and Ohmic contacts showed p-type-like behavior, and EBIC images suggested the formation of a p-type layer near the Ga2O3/AlN interface. Modelling indicated the formation of a two-dimensional hole layer at this interface, depending on the doping level and thickness of the kappa-Ga2O3.