Effect of oxygen content on p-type electrical conductivity in β-Ga2O3 films

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Park, Se-Rim and Chi, Zeyu and Sartel, Corinne and Koo, sang-Mo and Fregnaux, Matthieu and Zheng, Yunlin and Douglas, Sean and Penman, Lewis and Massabuau, Fabien and Tchelidze, Tamar and Chauveau, Jean-Michel and Chikoidze, Ekaterine (2025) Effect of oxygen content on p-type electrical conductivity in β-Ga2O3 films. Materials Science in Semiconductor Processing, 200. 110003. ISSN 1873-4081 (https://doi.org/10.1016/j.mssp.2025.110003)

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Abstract

β-Ga2O3 is a promising ultrawide bandgap semiconductor, but achieving reliable p-type conductivity remains a challenge, especially due to the scarcity of high-quality homoepitaxial p-type β-Ga2O3 layers. In this study, we investigate β-Ga2O3 thin films homoepitaxially grown on (-201) Fe doped β-Ga2O3 substrates via metal organic chemical vapor deposition under different oxygen-to-gallium (O/Ga) ratios. We examine the effect of oxygen content on the structural, electrical, and optical properties of thin films. The layer grown under oxygen-rich conditions (O/Ga = 6400) exhibited an enhanced crystallinity of the dominant (-201) orientation as indicated by a low full-width at half maximum (FWHM) of 72 arcsec in the X-ray diffraction rocking curve, a suppressed oxygen vacancy signal in X-ray photoelectron spectroscopy, and a two order of magnitude increase in hole concentration (p = 4.5 × 1015 cm−3 vs. 4.6 × 1013 cm−3 at 570 K), associated with a shallow acceptor level with an activation energy of 0.21 eV, likely due to V_Ga- - VO++ complex-like defect. In addition, both films exhibit hole mobility μH > 30 cm2/V·s over the measurement temperature range. These findings suggest that oxygen-rich growth conditions enhance both the crystallinity and native hole conductivity of β-Ga2O3, offering a promising route toward achieving controlled p-type behavior in this material.

ORCID iDs

Park, Se-Rim, Chi, Zeyu, Sartel, Corinne, Koo, sang-Mo, Fregnaux, Matthieu, Zheng, Yunlin, Douglas, Sean ORCID logoORCID: https://orcid.org/0009-0002-8729-2554, Penman, Lewis ORCID logoORCID: https://orcid.org/0000-0002-0147-9995, Massabuau, Fabien ORCID logoORCID: https://orcid.org/0000-0003-1008-1652, Tchelidze, Tamar, Chauveau, Jean-Michel and Chikoidze, Ekaterine;
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