Characterization of chromium impurities in β -Ga2O3
Year: 2025
Type: article
Abstract: Chromium is a common transition-metal impurity that is easily incorporated during crystal growth. It is perhaps best known for giving rise to the 694.3 nm (1.786 eV) emission in Cr-doped Al2O3, exploited in ruby lasers. Chromium has also been found in monoclinic gallium oxide, a wide-bandgap semiconductor being pursued for power electronics. In this work, we thoroughly characterize the behavior of Cr in Ga2O3 through theoretical and experimental techniques. β-Ga2O3 samples are grown with the floating zone method and show evidence of a sharp photoluminescence signal, reminiscent of ruby. We calculate the energetics of formation of Cr from first principles, demonstrating that Cr preferentially incorporates as a neutral impurity on the octahedral site. Cr possesses a quartet ground-state spin and has an internal transition with a zero-phonon line near 1.8 eV. By comparing the calculated and experimentally measured luminescence lineshape function, we elucidate the role of coupling to phonons and uncover features beyond the Franck–Condon approximation. The combination of strong emission with a small Huang–Rhys factor of 0.05 and a technologically relevant host material renders Cr in Ga2O3 attractive as a quantum defect.
Source: Journal of Applied Physics
DOI: 10.1063/5.0255859
Language: English
Topic: Ga2O3 and related materials
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,500
Funders: National Science Foundation, U.S. Department of Energy, China Scholarship Council, Norges Forskningsråd, Office of Science, University of California, Santa Barbara, Materials Research Science and Engineering Center, Harvard University, Multidisciplinary University Research Initiative, Office of Naval Research, Division of Materials Research, California NanoSystems Institute, Air Force Office of Scientific Research, Office of Naval Research Global, National Science Foundation Graduate Research Fellowship Program
Awards: G1028371657, G1110399006, G1141670404, G1157010347, G1230108060, G17160138, G2152459410, G2232042528, G241279073, G2450830071, G2692744044, G2693424129, G2760720504, Materials Research Science and Engineering Center at UCSB, G3349485200, G3400352658, G357145406, G3592558946, XSEDE 2.0: Integrating, Enabling and Enhancing National Cyberinfrastructure with Expanding Community Involvement, G3812616897, G401861217, G4281768896, G4720003262, G501274426, G5765906131, G5975534213, G6098521345, G6282714480, G6569974432, G6692005437, G6781789372, Graduate Research Fellowship Program (GRFP), G7408290410, G7463374569, G7518380869, Enabling Quantum Leap: Q-AMASE-i: Quantum Foundry at UCSB, MRI: Acquisition of a High Performance Central Computing Facility at University of California Santa Barbara, G872144517, G8876996369
OpenAlex ID: W4408458481