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Washington State University Institute of Materials Research



“Growth and characterization of photoconductive β-Ga2O3 Crystals” (2021-2024) – McCloy, McCluskey

Funding: Lawrence Livermore National Laboratory, Lab Directed R&D

This project, part of the larger “UWBG-LEAP: Ultra Wide Band Gap Laser Addressable Photoconductors,” has a central aim to achieve ultrawide bandgap crystals such as β-Ga2O3 with targeted sub-bandgap states required for optical excitation (i.e. photoconductivity).

“Fundamentals of Doping and Defects in Ga2O3 for High Breakdown Field Electronics” (2018-2024) – Lynn, McCloy, McCluskey, Weber

Funding: Department of Defense Multidisciplinary University Research Initiative (MURI), Air Force Office of Scientific Research

Partners:  University of Utah, Pennsylvania State University, University of Illinois-Urbana Champaign

IMR’s ultrawide bandgap research focuses on Gallium Oxide (Ga2O3), a promising material for high voltage breakdown devices and deep UV LEDs. Crystals of Ga2O3 are grown on-site with a Czochralski furnace at temperatures exceeding 1800C and later characterized with the purpose of studying optical, electronic, and defect properties. Measurement techniques include UV-vis-NIR, Hall Effect, XRD, DLTS, TEES and PAS. Doping of Ga2O3 crystals has been studied, with the intention of increasing material conductivity and improving crystallinity and Czochralski growth methods. Researchers at WSU work together with collaborators at The University of Utah in a tightly organized team to improve Ga2O3 device performance from a synthesis standpoint.


In publications below (most recent first), WSU authors are bolded.

Publications 2024:

  1. J. E. Stehr, M. Jansson, S. J. Pearton, J. S. McCloy, J. Jesenovec, B. L. Dutton, M. D. McCluskey, W. M. Chen, and I. A. Buyanova, “Color Center in β-Ga2O3 Emitting at the Telecom Range,” Applied Physics Letters, Applied Physics Letters, 124, 042104 (2024).
  2. Benjamin L. Dutton, Joel B. Varley, Cassandra Remple, Jani Jesenovec, Brooke K. Downing, Jimmy-Xuan Shen, Soroush Ghandiparsi, Adam Neal, Yunjo Kim, Andrew Green, Lars F. Voss, Matthew D. McCluskey, John S. McCloy, “Melt-grown semi-insulating Mn: β-Ga2O3 single crystals exhibiting unique visible absorptions and luminescence,” Journal of Vacuum Science and  Technology A, 42, 012801 (2024).
  3. Remple, C., Huso, J., Weber, M. H., McCloy, J. S., & McCluskey, M. D. Electron irradiation effects on the optical properties of Hf- and Zn-doped β-Ga2O3. Journal of Applied Physics, 135(18), 185702 (2024)
  4. Carrasco, D., M. Alonso-Orts, E. Nieto, R. Serna, J.M. San Juan, M.L. Nó, J. Jesenovec, J. McCloy, A. de Andrés, E. Nogales Díaz, and B. Méndez, “Chromium doped gallium oxide nanowire-based thermometer and the study of the anisotropic refractive index temperature dependence,” Proc. SPIE 12887 OPTO: Oxide-based Materials and Devices XV, 128870A (2024).

Publications 2023:

  1. Dutton, Remple, Jesenovec, Ghandiparsi, Gottlieb, Varley, Voss, McCluskey, and McCloy, “Polarization and orientation dependent optical properties in Czochralski-grown transition metal doped β-Ga2O3,” Proc. SPIE 12422, 1242205 (2023).
  2. Remple, Barmore, Jesenovec, McCloy, and McCluskey, “Photoluminescence spectroscopy of Cr3+ in β-Ga2O3 and (Al0.1Ga0.9)2O3,” Journal of Vacuum Science & Technology A, 41(2), 022702 (2023).
  3. Barmore, Jesenovec, McCloy, and McCluskey, “Photoluminescence of Cr3+ in β-Ga2O3 and (Al0.1Ga0.9)2O3 under pressure,” Journal of Applied Physics, 133(17), 175703 (2023).
  4. Carrasco, Nieto-Pinero, Alonso-Orts, Serna, San Juan, Nó, Jesenovec, McCloy, Nogales, and Méndez, “Temperature-Dependent Anisotropic Refractive Index in β-Ga2O3: Application in Interferometric Thermometers,” Nanomaterials, 13(6), 1126 (2023).
  5. Balog, Miao, Bachu, Jesenovec, Dutton, McCloy, Alem, “High Resolution Scanning Transmission Electron Microscopy (S/TEM) Investigation Of Common Defects In Scandium and Aluminum Alloyed β-Ga2O3,” Microscopy and Microanalysis, 29(Supp1), 1779.

Publications 2022:

  1. McCloy, Jesenovec, Dutton, Pansegrau, Remple, Weber, Swain, McCluskey, and Scarpulla, “Growth and defect characterization of doped and undoped β-Ga2O3 crystals,” Proc. SPIE 12002 SPIE OPTO: Oxide-based Materials and Devices XIII, 1200205 (2022).
  2. Jani Jesenovec, Cassandra Remple, Jesse Huso, Benjamin Dutton, Parker Toews, Matthew D. McCluskey, John S. McCloy, “Photodarkening and Dopant Segregation in Cu-doped β-Ga2O3 Czochralski Single Crystals,” Journal of Crystal Growth, 578, 126419 (2022).
  3. Jesenovec, Pansegrau, McCluskey, McCloy, Gustafson, Halliburton, and Varley, “Persistent Room-Temperature Photodarkening in Cu-Doped β-Ga2O3,” Physical Review Letters, 128(7), 077402 (2022).
  4. Gustafson, Giles, Holloway, Lenyk, Jesenovec, McCloy, McCluskey, and Halliburton, “Cu2+ and Cu3+ acceptors in β-Ga2O3 crystals: A magnetic resonance and optical absorption study,” Journal of Applied Physics, 131(6), 065702 (2022).
  5. Jesenovec, Dutton, Stone-Weiss, Chmielewski, Saleh, Peterson, Alem, Krishnamoorthy, and McCloy, “Alloyed β-(AlxGa1−x)2O3 bulk Czochralski single β-(Al0.1Ga0.9)2O3 and polycrystals β-(Al0.33Ga0.66)2O3, β-(Al0.5Ga0.5)2O3), and property trends,” Journal of Applied Physics, 131(15), 155702 (2022).
  6. Gustafson, Giles, Holloway, Jesenovec, Dutton, McCloy, McCluskey, and Halliburton, “Transition-metal ions in β-Ga2O3 crystals: Identification of Ni acceptors,” Journal of Applied Physics, 132(18), 185705 (2022).
  7. Jesenovec, Dutton, Remple, Smith-Gray, Murugesan, Peterson, Downing, Krishnamoorthy, McCluskey, and McCloy, “Alternative alloy to increase bandgap in Gallium Oxide, β-(ScxGa1-x)2O3, and rare earth Stark luminescence,” Journal of Crystal Growth, 596, 126823 (2022).
  8. Cooke, Ranga, Jesenovec, Bhattacharyya, Cheng, Wang, McCloy, Krishnamoorthy, Scarpulla, and Sensale-Rodriguez, “Photoluminescence microscopy as a noninvasive characterization method for defects in gallium oxide and aluminum gallium oxide epitaxial films,” Optical Materials Express, 12(11), 4341-4353 (2022).
  9. Ghadbeigi, Sun, Jesenovec, Bhattacharyya, McCloy, Krishnamoorthy, Scarpulla, and Sensale-Rodriguez, “Electronic and ionic conductivity in β-Ga2O3 single crystals,” Journal of Applied Physics, 131(8), 085102 (2022).
  10. Cooke, Ranga, Jesenovec, McCloy, Krishnamoorthy, Scarpulla, and Sensale-Rodriguez, “Effect of extended defects on photoluminescence of gallium oxide and aluminum gallium oxide epitaxial films,” Scientific Reports, 12(1), 3243 (2022).
  11. Jesenovec and McCloy, Weighing up the options for gallium oxide crystal growth, Compound Semiconductor Magazine, 28(7), p. 42-46 Oct 2022.

Publications 2021:

  1. C. Remple, J. Huso, and M. McCluskey, “Photoluminescence and Raman mapping of β-Ga2O3,” AIP Advances, 11(10), 105006 (2021).
  2. Adrian Chmielewski, Ziling Deng, Muad Saleh, Jani Jesenovec, Wolfgang Windl, Kelvin Lynn, John McCloy, Nasim Alem, “Atomic-Scale Characterization of Structural and Electronic Properties of Hf doped β-Ga2O3Applied Physics Letters, 119, 172102 (2021).
  3. Christopher Pansegrau, Jani Jesenovec, John McCloy, Matthew McCluskey, “Zinc-hydrogen and zinc-iridium pairs in β-Ga2O3,” Applied Physics Letters, 119(10), 102104 (2021),
  4. Jani Jesenovec, Marc Weber, Christopher Pansegrau, Matthew McCluskey, Kelvin Lynn, and John McCloy, “Gallium Vacancy Formation in Oxygen Annealed β-Ga2O3,” Journal of Applied Physics, 129(24), 245701 (2021).
  5. J. Jesenovec, J. Varley, S.E. Karcher, and J.S. McCloy, “Electronic and optical properties of Zn-doped β-Ga2O3 Czochralski single crystals,” Journal of Applied Physics, 129(22), 225702 (2021).
  6. Santosh Swain, Marc Weber, Jani Jesenovec, Muad Saleh, Kelvin Lynn, John McCloy, “Compensation by gallium vacancies and iron acceptors in β-Ga2O3,” Physical Review Applied, 15(5), 054010 (2021).
  7. Timothy Gustafson, Jani Jesenovec, Christopher Lenyk, Nancy Giles, John McCloy, Matthew McCluskey, and Larry Halliburton, “Zn acceptors in β-Ga2O3 crystals,” Journal of Applied Physics, 129(15), 155701 (2021).

Publications 2018-2020

  • J. Ritter, J. Huso, P.T. Dickens, J.B. Varley, K.G. Lynn, and M.D. McCluskey, “Compensation and hydrogen passivation of magnesium acceptors in β-Ga2O3,” Applied Physics Letters, 113(5), 052101 (2018).
  • Wang, Y., P.T. Dickens, J.B. Varley, X. Ni, E. Lotubai, S. Sprawls, F. Liu, V. Lordi, S. Krishnamoorthy, S. Blair, K.G. Lynn, M. Scarpulla, and B. Sensale-Rodriguez, “Incident wavelength and polarization dependence of spectral shifts in β-Ga2O3 UV photoluminescence,” Scientific Reports, 8(1), 18075 (2018).
  • Saleh, M., A. Bhattacharyya, J.B. Varley, S. Swain, J. Jesenovec, S. Krishnamoorthy, and K. Lynn, “Electrical and optical properties of Zr doped β-Ga2O3 single crystals,” Applied Physics Express, 12(8), 085502 (2019).
  • Ritter, Lynn, and McCluskey, “Hydrogen passivation of calcium and magnesium doped β-Ga2O3,” Proc. SPIE 10919, 109190Z (2019).
  • Ritter, Lynn, and McCluskey, “Iridium-related complexes in Czochralski-grown β-Ga2O3,” Journal of Applied Physics, 126(22), 225705 (2019).
  • Saleh, M., J.B. Varley, J. Jesenovec, A. Bhattacharyya, S. Krishnamoorthy, S. Swain, and K. Lynn, “Degenerate doping in β-Ga2O3 single crystals through Hf-doping,” Semiconductor Science and Technology, 35(4), 04LT01 (2020).
  • McCluskey, “Point defects in Ga2O3,” Journal of Applied Physics, 127(10), 101101 (2020).
  • Sun, Ooi, Bhattacharyya, Saleh, Krishnamoorthy, Lynn, and Scarpulla, “Defect states and their electric field-enhanced electron thermal emission in heavily Zr-doped β-Ga2O3 crystals,” Applied Physics Letters, 117(21), 212104 (2020).
  • Zirconium doping improves gallium oxide. Compound Semiconductor Magazine, 25(6), p. 76 Aug-Sept 2019.