Electrical properties of α-Ga2O3 films grown by halide vapor phase epitaxy on sapphire with α-Cr2O3 buffers
Abstract
We report on growth and electrical properties of α-Ga2O3 films prepared by halide vapor phase epitaxy (HVPE) at 500 °C on α-Cr2O3 buffers predeposited on sapphire by magnetron sputtering. The α-Cr2O3 buffers showed a wide microcathodoluminescence (MCL) peak near 350 nm corresponding to the α-Cr2O3 bandgap and a sharp MCL line near 700 nm due to the Cr+ intracenter transition. Ohmic contacts to Cr2O3 were made with both Ti/Au or Ni, producing linear current–voltage (I–V) characteristics over a wide temperature range with an activation energy of conductivity of ∼75 meV. The sign of thermoelectric power indicated p-type conductivity of the buffers. Sn-doped, 2-μm-thick α-Ga2O3 films prepared on this buffer by HVPE showed donor ionization energies of 0.2–0.25 eV, while undoped films were resistive with the Fermi level pinned at EC of 0.3 eV. The I–V and capacitance–voltage (C–V) characteristics of Ni Schottky diodes on Sn-doped samples using a Cr2O3 buffer indicated the presence of two face-to-face junctions, one between n-Ga2O3 and p-Cr2O3, the other due to the Ni Schottky diode with n-Ga2O3. The spectral dependence of the photocurrent measured on the structure showed the presence of three major deep traps with optical ionization thresholds near 1.3, 2, and 2.8 eV. Photoinduced current transient spectroscopy spectra of the structures were dominated by deep traps with an ionization energy of 0.95 eV. These experiments suggest another pathway to obtain p–n heterojunctions in the α-Ga2O3 system.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 03, 2022
- Source ID
- 10.1063/5.0090832
Entities
People
- A. Y. Polyakov
- A.A. Vasil'ev
- Bogdan O. Kushnarev
- Eugene Yakimov
- Ivan Shchemerov
- M. P. Scheglov
- Sergey Stepanov
- Stephen Pearton
- А. I. Kochkova
- А. V. Аlmaev
- А. В. Черных
- А. И. Печников
- В. И. Николаев
Organizations
- Defense Threat Reduction Agency
- Division of Materials Research
- Institute of Microelectronics
- Ioffe Institute
- National University of Science and Technology
- Russian Science Foundation
- Tomsk State University
- University of Florida