Study on vdW Epitaxy Mechanism and Stress Modulation of Large-Size GaN Microwave Material
Based on metal organic chemical vapor deposition(MOCVD),growth mechanism and stress modulation of van der Waals(vdW)heteroepitaxial GaN microwave material were studied with few-layer BN as an interlayer on 4-inch sapphire substrates.The influence of AlN nucleate process on growth mechanism of GaN buffer layer and its correlation with crystalline quality,stress,and electrical properties were discussed.A stress modulation scheme based on AlN/AlGaN composite nucleation process is proposed,achieving stress well in control for large-size vdW heteroepitaxy firstly.The as-grown GaN micro wave material possesses a wafer bow of+20.4 μm,full width at half maximum of GaN(002)/(102)peaks of 471.6/933.5 arcsec,root-mean-square roughness of 0.52 nm and electron mobility of 2 000 cm2/(V·s).Finally,large-size wafe-scale GaN microwave material was successfully separated from sapphire substrate by a mechanical lift-off process,providing convenience for transfering to high thermal conductivity substrates and creating conditions for fabricating high-power RF devices.
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维普
