Two-Dimensional Hole Gas Formation at the Κ-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 κ-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 κ-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 κ-Ga2O3.