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

      Researchers from the  University of Massachusetts Lowell have published a dissertation titled "Low-pressure CVD grown Si-doped β-Ga₂O₃ films with promising electron mobilities and high growth rates" in Applied Physics Letters.

Abstract

      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 (⁠-201) 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 (⁠-201) 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.

DOI：

https://doi.org/10.1063/5.0245559