Free-standing AlxGa1-xAs heterostructures by gas-phase etching of germanium

Author(s): G. D. Cole, Y. Bai, M. Aspelmeyer, E. A. Fitzgerald

Journal: Applied Physics Letters

Volume: 96

Page(s): 261102

Year: 2010

DOI Number: 10.1063/1.3455104

Link: Link to publication


We outline a facile fabrication technique for the realization of free-standing AlxGa1−xAs heterostructures of arbitrary aluminum content. Utilizing xenon difluoride (XeF2) we rapidly and selectively remove a sacrificial germanium (Ge) underlayer in a room temperature gas-phase etching procedure. We demonstrate two possibilities for exploiting this unique process: (1) bulk micromachining of a suspended high-frequency low-dissipation micro-optomechanical resonator consisting of an epitaxial GaAs/AlAs multilayer grown on a Ge substrate and (2) epitaxial lift-off of a GaAs film via removal of an embedded Ge sacrificial layer, resulting in lateral etch rates up to 3 mm/h and a conservative selectivity of ∼ 106.

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