High-Mobility Ge-Doped β-Ga2O3 Growth on Sapphire by Low-Pressure Chemical Vapor Deposition
Abstract
In this work, high-quality Ge-doped (-201) β-Ga2O3 thin films were heteroepitaxially grown on c-plane sapphire substrates with offcut angles of 0 deg, 2 deg, 6 deg, and 8 deg using low-pressure chemical vapor deposition (LPCVD). Increasing sapphire offcut promoted step-flow growth, resulting in improved terrace alignment, reduced surface roughness, and enhanced crystalline quality. Phase-pure monoclinic β-Ga2O3 with strong (-201) preferential orientation was confirmed by X-ray diffraction and Raman spectroscopy, while X-ray photoelectron spectroscopy revealed near-stoichiometric composition with an O/Ga ratio of 1.48. Electrical transport properties exhibited a strong dependence on substrate offcut angle, with room-temperature Hall mobility increasing from 15 to 117 cm2/V s as the offcut angle increased from 0 deg to 6 deg, across carrier concentrations spanning 1.43 × 1017 to 2.75 × 1018 cm−3. The 6 deg offcut sample achieved a room-temperature mobility of 117 cm2/V s at a carrier concentration of 1.43 × 1017 cm−3 and a peak low-temperature mobility of 337 cm2/V s at 128 K with a carrier concentration of 8.96 × 1016 cm−3, representing the highest reported room-temperature and low-temperature mobilities for Ge-doped β-Ga2O3 films grown on sapphire substrates. Carrier concentration and mobility data were analyzed using charge-neutrality and Boltzmann transport models incorporating donor activation together with polar optical phonon, ionized impurity, neutral impurity, acoustic deformation potential, and dislocation scattering mechanisms. The fitting revealed shallow donor activation energies of 12.5-19 meV, a deeper donor level at 80 meV, low acceptor compensation (< 5 × 1015 cm−3), and threading dislocation densities on the order of 109 cm−2.
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BibTeX
@misc{ibreljic2026highmobility,
title = {{High-Mobility Ge-Doped $β$-Ga$_2$O$_3$ Growth on Sapphire by Low-Pressure Chemical Vapor Deposition}},
author = {Ahmed Ibreljic and Saleh Ahmed Khan and Sourav Sarker and Ibrahim Isah and Stephen Margiotta and Michael Davenport and Stephen Lam and Anhar Bhuiyan},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.10908},
eprint = {2607.10908},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.10908},
}
RIS
TY - UNPB
TI - High-Mobility Ge-Doped β-Ga_2O_3 Growth on Sapphire by Low-Pressure Chemical Vapor Deposition
AU - Ahmed Ibreljic
AU - Saleh Ahmed Khan
AU - Sourav Sarker
AU - Ibrahim Isah
AU - Stephen Margiotta
AU - Michael Davenport
AU - Stephen Lam
AU - Anhar Bhuiyan
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2607.10908
UR - https://arxiv.org/abs/2607.10908
AB - In this work, high-quality Ge-doped (-201) β-Ga_2O_3 thin films were heteroepitaxially grown on c-plane sapphire substrates with offcut angles of 0 deg, 2 deg, 6 deg, and 8 deg using low-pressure chemical vapor deposition (LPCVD). Increasing sapphire offcut promoted step-flow growth, resulting in improved terrace alignment, reduced surface roughness, and enhanced crystalline quality. Phase-pure monoclinic β-Ga_2O_3 with strong (-201) preferential orientation was confirmed by X-ray diffraction and Raman spectroscopy, while X-ray photoelectron spectroscopy revealed near-stoichiometric composition with an O/Ga ratio of 1.48. Electrical transport properties exhibited a strong dependence on substrate offcut angle, with room-temperature Hall mobility increasing from 15 to 117 cm^2/V s as the offcut angle increased from 0 deg to 6 deg, across carrier concentrations spanning 1.43 × 10^17 to 2.75 × 10^18 cm^−3. The 6 deg offcut sample achieved a room-temperature mobility of 117 cm^2/V s at a carrier concentration of 1.43 × 10^17 cm^−3 and a peak low-temperature mobility of 337 cm^2/V s at 128 K with a carrier concentration of 8.96 × 10^16 cm^−3, representing the highest reported room-temperature and low-temperature mobilities for Ge-doped β-Ga_2O_3 films grown on sapphire substrates. Carrier concentration and mobility data were analyzed using charge-neutrality and Boltzmann transport models incorporating donor activation together with polar optical phonon, ionized impurity, neutral impurity, acoustic deformation potential, and dislocation scattering mechanisms. The fitting revealed shallow donor activation energies of 12.5-19 meV, a deeper donor level at 80 meV, low acceptor compensation (< 5 × 10^15 cm^−3), and threading dislocation densities on the order of 10^9 cm^−2.
ER -