Properties of κ‐Ga₂O₃ Prepared by Epitaxial Lateral Overgrowth

Abstract

The structural and electrical properties of undoped and Sn doped κ‐Ga2O3 layers grown by epitaxial lateral overgrowth on TiO2/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 EC‐0.7 eV, and deep electron traps at EC‐0.5 eV and EC‐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 ≈ 1013 cm−3, and deep trap spectra determined by electron traps at EC‐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 ≈ 1019 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‐Ga2O3 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‐Ga2O3/GaN interface.

Proton damage effects in double polymorph γ/β-Ga2O3 diodes

“…S1, ESI†), indicating that the centers have a sizable barrier for capture of electrons, similar to so-called DX-like defects. 19 Notably, similar behavior was recently reported for hydrogenated β-Ga 2 O 3 40 and κ-Ga 2 O 3 41 films as well. In that context, it seems that H behaves similarly in Ga 2 O 3 polymorphs even though the symmetry of the β-, κ-, and γ-polymorphs and consequently the energetics of the different H configurations are different.…”

Editors’ Choice—Structural, Electrical, and Luminescent Properties of Orthorhombic κ-Ga2O3 Grown by Epitaxial Lateral Overgrowth

“…The Full Widths at Half Maximum (FWHM) of the symmetric 004 HRXRD rocking curves was 4 arcminutes, for skew-symmetric reflection 206 it was 8 arcminutes, which is among the lowest ever reported for κ-Ga 2 O 3 films. 23 Mind also that the measured FWHM were collected from the overall area of the wings and the windows regions and the actual value in the wings could be lower than these averaged figures. STEM image acquired by high-angle annular dark-field detector (HAADF) of ELOG κ-Ga 2 O 3 film is shown in Fig.…”

“…This is most likely the consequence of the high density of compensating point defect acceptor centers, most likely Ga vacancies or their complexes. As shown in our recent paper 23 the situation can be seriously remedied by treating the samples in dense hydrogen plasma, which allows to increase the net donor density to over 10 18 cm −3 .…”

“…The detailed description of the results obtained for both types of masks for undoped and Sn doped films can be found in our recent paper. 23 In what follows we'll concentrate on studying the properties of the Sn doped films grown with stripe mask.…”

Photoelectron Holographic Study for Atomic Site Occupancy for Si Dopants in Si-Doped κ-Ga2O3(001)

“…According to previous studies, dopant atomic positions of Ga are replaced by Si, that is, Si Ga in κ-Ga 2 O 3 . 7,20 Therefore, PEH simulations were performed for the Octa, Penta, and Tetra Si Ga sites. Figure 5 shows the experimental and simulated Si 2p PEHs for the Octa, Penta, and Tetra Si Ga sites.…”