Proving optical anisotropy and polarization effects in β-Ga2O3 nanomembranes via X-Ray excited optical luminescence

Monoclinic beta-Ga2O3 is a key representative material of the ultrawide-bandgap semiconductor family. The distinct atomic arrangement in beta-Ga2O3 introduces two coordination environments for Ga ions, resulting in pronounced anisotropy in its optical, electronic, and thermal properties. In this stu...

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Bibliographic Details
Authors: Pérez Peinado, Paula, Dolado, J., Alcázar Ruano, Pedro Luis, Carrasco Madrigal, Daniel, Martínez Casado, María Ruth, Bonino, Valentina, Martínez Criado, Gema, Jesenovec, Jani, McCloy, John S., Domínguez-Adame Acosta, Francisco, Quereda, Jorge, Nogales Díaz, Emilio, Méndez Martín, María Bianchi
Format: article
Publication Date:2025
Country:España
Institution:Universidad Complutense de Madrid (UCM)
Repository:Docta Complutense
Language:English
OAI Identifier:oai:docta.ucm.es:20.500.14352/125034
Online Access:https://hdl.handle.net/20.500.14352/125034
Access Level:Open access
Keyword:538.9
Gallium oxide
Nanomembranes
Polarizations
X-ray absorption
X-ray excited optical luminescence
Física de materiales
2211 Física del Estado Sólido
Description
Summary:Monoclinic beta-Ga2O3 is a key representative material of the ultrawide-bandgap semiconductor family. The distinct atomic arrangement in beta-Ga2O3 introduces two coordination environments for Ga ions, resulting in pronounced anisotropy in its optical, electronic, and thermal properties. In this study, a synchrotron nanoprobe to investigate the anisotropic optical properties of well-oriented (100) beta-Ga2O3 nanomembranes with a thickness of 200 nm, produced through mechanical exfoliation, is employed. Polarization-resolved X-ray excited optical luminescence (XEOL) measurements reveal a strong ultraviolet (UV) emission band at 3.4 eV, which is strongly polarized along the c-axis. Additionally, XEOL data show blue (2.9 eV) and deep-UV (3.8 eV) emissions. Notably, the deep-UV band, rarely reported in conventional photoluminescence studies, is attributed to the presence of Ga vacancies, as supported by first-principles calculations. Polarization-dependent X-ray absorption near-edge structure (XANES) spectroscopy allows one to probe the distinct symmetries of the b and c crystallographic planes. Furthermore, by combining XANES and XEOL, this study investigates the site-specific contributions of Ga ions to the luminescence process. These findings highlight the potential of beta-Ga2O3 nanomembranes as a robust material platform for developing polarization-sensitive devices. The pronounced anisotropy of beta-Ga2O3 causes orientation-dependent optoelectronic properties, making it a highly promising candidate for a wide range of advanced applications

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