Properties of κ‐Ga₂O₃ Prepared by Epitaxial Lateral Overgrowth

The structural and electrical properties of undoped and Sn doped κ‐Ga 2 O 3 layers grown by epitaxial lateral overgrowth on TiO 2 /sapphire substrates using stripe and point masks show that the crystalline structure of the films can be greatly improved relative to conventional planar growth. The undoped films are semi‐insulating, with the Fermi level pinned near E C ‐0.7 eV, and deep electron traps at E C ‐0.5 eV and E C ‐0.3 eV are detectable in thermally stimulated current and photoinduced current transient spectra measurements. Low concentration Sn doping results in net donor concentrations of ≈ 10 13 cm −3 , and deep trap spectra determined by electron traps at E C ‐0.5 eV, and deep acceptors with an optical ionization threshold near 2 and 3.1 eV. Treatment of the samples in hydrogen plasma at 330 °C increases the donor density near the surface to ≈ 10 19 cm −3 . Such samples show strong persistent photocapacitance and photoconductivity, indicating the possible DX‐like character of the centers involved. For thin (5 µm) κ‐Ga 2 O 3 films grown on GaN/sapphire templates, p‐type‐like behavior is unexpectedly observed in electrical properties and we discuss the possible formation of a 2D hole gas at the κ‐Ga 2 O 3 /GaN interface.