Low-pressure CVD grown Si-doped β-Ga2O3 films with promising electron mobilities and high growth rates

In this work, we systematically investigated the growth of Si-doped β-Ga2O3 films using low-pressure chemical vapor deposition (LPCVD) system, achieving high room-temperature Hall mobilities of 162 and 149 cm2/V·s at carrier concentrations of 1.51 × 1017 and 1.15 × 1017 cm−3, respectively, for homoepitaxial (010) β-Ga2O3 film grown on β-Ga2O3 substrates and heteroepitaxial (2¯01) β-Ga2O3 film grown on off-axis c-sapphire substrate with 6° miscut-representing the highest mobilities reported for LPCVD-grown β-Ga2O3 materials. Carrier concentrations were precisely tuned by varying SiCl4 flow rates at a growth temperature of 1000 °C, resulting in concentrations ranging from 1.15 × 1017 to 1.19 × 1019 cm−3 as confirmed by both Hall and capacitance–voltage (C–V) measurements. The films exhibited high crystalline quality, confirmed by high resolution x-ray diffraction and Raman spectroscopy, indicating phase purity and structural integrity. Surface morphologies characterized by field-emission scanning electron microscope and atomic force microscopy showed a strong correlation between carrier concentrations and surface smoothness, with lower concentration resulting in reduced RMS roughness. Secondary Ion Mass Spectrometry analysis revealed uniform Si incorporation, with low carbon, hydrogen, and chlorine impurities below detection limits, indicating high purity of the films. A high low-temperature peak mobility exceeding >843 cm2/V·s was achieved at a carrier concentration of 1.74 × 1016 cm−3 for a (2¯01) β-Ga2O3 heteroepitaxial film at 80 K, highlighting the high purity and low compensation of these films. These findings emphasize the potential of LPCVD growth system for producing high-purity β-Ga2O3 films with thickness ranging between ∼2.3 and 11.7 μm and faster growth rates (∼4.7–17 μm/h), promising transport properties, controllable doping, and scalability for developing high-power vertical devices.