Electrical and Recombination Properties of Polar Orthorhombic κ-Ga(2)O(3) Films Prepared by Halide Vapor Phase Epitaxy

In this study, the structural and electrical properties of orthorhombic κ-Ga(2)O(3) films prepared using Halide Vapor Phase Epitaxy (HVPE) on AlN/Si and GaN/sapphire templates were studied. For κ-Ga(2)O(3)/AlN/Si structures, the formation of two-dimensional hole layers in the Ga(2)O(3) was studied and, based on theoretical calculations, was explained by the impact of the difference in the spontaneous polarizations of κ-Ga(2)O(3) and AlN. Structural studies indicated that in the thickest κ-Ga(2)O(3)/GaN/sapphire layer used, the formation of rotational nanodomains was suppressed. For thick (23 μm and 86 μm) κ-Ga(2)O(3) films grown on GaN/sapphire, the good rectifying characteristics of Ni Schottky diodes were observed. In addition, deep trap spectra and electron beam-induced current measurements were performed for the first time in this polytype. These experiments show that the uppermost 2 µm layer of the grown films contains a high density of rather deep electron traps near E(c) − 0.3 eV and E(c) − 0.7 eV, whose presence results in the relatively high series resistance of the structures. The diffusion length of the excess charge carriers was measured for the first time in κ-Ga(2)O(3). The film with the greatest thickness of 86 μm was irradiated with protons and the carrier removal rate was about 10 cm(−1), which is considerably lower than that for β-Ga(2)O(3).