【Epitaxy Papers】Effect of oxygen content on p-type electrical conductivity in β-Ga₂O₃ films

      Researchers from the Kwangwoon University have published a dissertation titled "Effect of oxygen content on p-type electrical conductivity in β-Ga₂O₃ films" in Materials Science in Semiconductor Processing.

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 (-201) dominant  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^--V_O⁺⁺  complex-like defect. In addition, both films exhibit hole mobility μ_H > 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.

DOI：

https://doi.org/10.1016/j.mssp.2025.110003