HVPE-growth of Si-doped β-Ga₂O₃ on Sapphire: Influence of substrate offcut on structural and electrical properties
Year: 2026
Type: other
Abstract: In this work, Si-doped β-Ga₂O₃ films were heteroepitaxially grown on sapphire substrates using halide vapor phase epitaxy (HVPE). The influence of sapphire offcut on growth kinetics, surface morphology, crystalline quality, and electrical transport properties was systematically investigated. Growth kinetics studies revealed a strong dependence of deposition rate on HCl flow, growth pressure, and source-to-substrate distance, with growth rates reaching up to 30 μm/hr. Increasing sapphire offcut angle from 0{degree sign} to 8{degree sign} promoted a transition from multidirectional growth to highly aligned terrace-dominated surfaces, reducing the surface roughness from 14.69 to 2.74 nm. The improved surface morphology was accompanied by enhanced crystalline quality, with phase-pure (-2 01)-oriented β-Ga₂O₃ growth and a reduction in the rocking-curve full width at half maximum from 994 to 414 arcsec, as the sapphire offcut increased. Electrical characterization of films grown on 6{degree sign} offcut substrate yielded carrier concentrations ranging from 1.0×10¹⁷ to 3.4×10¹⁸ cm⁻³. A maximum room-temperature electron mobility of 100 cm²/V·s was achieved at a carrier concentration of 1.0×10¹⁷ cm⁻³, representing the highest reported room-temperature mobility for HVPE-grown β-Ga₂O₃ on a foreign substrate. Analysis of the temperature-dependent transport characteristics yielded donor activation energies of 35 and 90 meV together with a low acceptor concentration of 3×10¹⁵ cm⁻³, consistent with the improved crystalline quality achieved on the offcut sapphire substrates. These results demonstrate that HVPE is capable of producing high-quality β-Ga₂O₃ heteroepitaxial layers with good crystalline quality and carrier transport characteristics, providing a promising pathway for scalable β-Ga₂O₃ epitaxy on low-cost foreign substrates.
Source: AIP Publishing
Language: English
Topic: Ga2O3 and related materials
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214724939