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arXiv · 2207.12582

MOCVD growth and band offsets of \k{appa}-phase Ga2O3 on sapphire, GaN, AlN and YSZ substrates

A F M Anhar Uddin Bhuiyan·Zixuan Feng·Hsien-Lien Huang·Lingyu Meng·Jinwoo Hwang·Hongping Zhao
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Abstract

Epitaxial growth of \k{appa}-phase Ga2O3 thin films are investigated on c-plane sapphire, GaN- and AlNon-sapphire, and (100) oriented yttria stabilized zirconia (YSZ) substrates via metalorganic chemical vapor deposition (MOCVD). The structural and surface morphological properties are investigated by comprehensive material characterization. Phase pure \k{appa}-Ga2O3 films are successfully grown on GaN-, AlN-on sapphire, and YSZ substrates through a systematical tuning of the growth parameters including the precursor molar flow rates, chamber pressure and growth temperature, whereas the growth on c-sapphire substrates leads to a mixture of \b{eta}- and \k{appa}polymorphs of Ga2O3 under the investigated growth conditions. The influence of the crystalline structure, surface morphology and roughness of \k{appa}-Ga2O3 films grown on different substrates are investigated as a function of precursor flow rate. High resolution scanning transmission electron microscopy (HR-STEM) imaging of \k{appa}-Ga2O3 films reveals abrupt interfaces between the epitaxial film and the sapphire, GaN and YSZ substrates. The growth of single crystal orthorhombic \k{appa}Ga2O3 films is confirmed by analyzing the STEM nano-diffraction pattern. The chemical composition, surface stoichiometry, and the bandgap energies of \k{appa}-Ga2O3 thin films grown on different substrates are studied by high resolution x-ray photoelectron spectroscopy (XPS) measurements. The type-II (staggered) band alignments at three interfaces between \k{appa}-Ga2O3 and c-sapphire, AlN, and YSZ substrates are determined by XPS, with the exception of \k{appa}-Ga2O3/GaN interface, which shows type I (straddling) band alignment.

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A F M Anhar Uddin Bhuiyan, Zixuan Feng, Hsien-Lien Huang, Lingyu Meng, Jinwoo Hwang, Hongping Zhao. 2022-07-26. MOCVD growth and band offsets of \k{appa}-phase Ga2O3 on sapphire, GaN, AlN and YSZ substrates. https://arxiv.org/abs/2207.12582

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