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Direct Imaging on Strain Relaxation of MBE-grown Single Phase alpha-(Al,Ga)<sub>2</sub>O<sub>3</sub> on m-sapphire Substrate in Atomic Resolution Using Scanning Transmission Electron Microscopy

ORAL

Abstract

MBE-grown corundum structured alpha-Ga2O3 on c-plane sapphire substrates often contains considerable amount of beta-Ga2O3 due to c-plane facets. Recently, a successful MBE-growth of pure alpha-(Al, Ga)2O3 on m-plane sapphire was reported. Here, we show the relaxation mechanism of such films by performing strain analysis with scanning transmission electron microscopy (STEM). The films are partially relaxed through dislocation cores at the interface, some of which tend to climb up into the film. High angle annular dark field (HAADF)-STEM images in plan-view shows the formation of very thin gamma-Ga2O3 at the interface occupying less than 1% area density. Owing to its defect spinel-type structure that requires two cation vacancies, gamma-Ga2O3 is believed to form naturally at the interface to accommodate the strain arising from lattice mismatch.

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Presenters

  • Celesta Chang

    Cornell University, Department of Physics, Cornell University

Authors

  • Celesta Chang

    Cornell University, Department of Physics, Cornell University

  • Riena Jinno

    Electrical and Computer Engineering, Cornell University

  • Debdeep Jena

    School of Electrical and Computer Engineering, Cornell University, Cornell University, Electrical and Computer Engineering, Cornell University

  • Huili Grace Xing

    Cornell University, Electrical and Computer Engineering, Cornell University

  • David Anthony Muller

    Cornell University, School of Applied and Engineering Physics, Cornell University, Applied and Engineering Physics, Cornell University, School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA