Editors’ Choice—Structural, Electrical, and Luminescent Properties of Orthorhombic κ-Ga<sub>2</sub>O<sub>3</sub> Grown by Epitaxial Lateral Overgrowth
В. И. Николаев, A. Y. Polyakov, А. V. Myasoedov, I. S. Pavlov, Anatolii V. Morozov, А. И. Печников, In‐Hwan Lee, E. B. Yakimov, A.A. Vasil'ev, M. P. Scheglov, А. I. Kochkova, S. J. Pearton
Abstract
The properties of orthorhombic κ-Ga 2 O 3 films grown by Epitaxial Lateral Overgrowth (ELOG) were studied by Scanning Transmission Electron Microscopy (STEM), X-ray diffraction, capacitance-voltage profiling, Microcathodoluminescence (MCL) spectroscopy and imaging. ELOG mask was formed by deposition of SiO 2 stripes on TiO 2 buffer prepared on basal plane sapphire, with the stripes going along the [11 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> <mml:mo>̅</mml:mo> </mml:mover> </mml:math> 0] direction of sapphire. κ-Ga 2 O 3 ELOG growth was performed using Halide Vapor Phase Epitaxy (HVPE), with ELOG wing of the structure formed by lateral overgrowth over the 20 μ m-wide SiO 2 stripes, while growth in between the stripes proceeded initially by vertical growth in the 5- μ m-wide windows. TEM analysis showed that the material in the windows comprised 120 o rotational nanodomains typical of κ-Ga 2 O 3 , while, in the wing regions, the material was single-domain monocrystalline. The films were conducting, with the net donor density close to 10 13 cm −3 . The data suggested the material in the windows have much higher resistance than in the wings. MCL spectra and imaging revealed much higher density of nonradiative recombination centers in the windows than in the wings.