Optical properties of 2-inch β-Ga₂O₃ crystals grown by vertical Bridgman method

Abstract β-Ga2O3, an ultrawide bandgap semiconductor (4.8 eV, 8 MV cm⁻¹ breakdown field), is vital for high-voltage electronics. This study employs the vertical Bridgman (VB) method with Pt-Rh crucibles to grow 2-inch (010)-oriented single crystals (unintentionally doped, Sn/Fe-doped), addressing cost and scalability issues of conventional techniques. X-ray diffraction shows high crystallinity (FWHM ~20 arcsec, ≤7% variation). Sn-doped samples exhibit uniform resistivity (2×10⁻² Ω·cm) via Ga vacancy-mediated diffusion. Spectroscopy reveals passive Rh doping behavior induces a 0.05–0.09 eV bandgap extension and a 2.9 eV absorption threshold, with reducing Fermi level–VBM separation by 0.34 eV. The VB technique provides a scalable, low-cost pathway for industrial production of high-quality β-Ga₂O₃ substrates, offering critical insights into Rh doping effects that advance strategies for p-type conductivity and next-generation power device applications.