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

Garrett D. Cole, Yu Bai, Markus Aspelmeyer, Eugene A. Fitzgerald
2010 Applied Physics Letters  
We outline a facile fabrication technique for the realization of free-standing Al x Ga 1−x As heterostructures of arbitrary aluminum content. Utilizing xenon difluoride ͑XeF 2 ͒ we rapidly and selectively remove a sacrificial germanium ͑Ge͒ underlayer in a room temperature gas-phase etching procedure. We demonstrate two possibilities for exploiting this unique process: ͑1͒ bulk micromachining of a suspended high-frequency low-dissipation micro-optomechanical resonator consisting of an epitaxial
more » ... ing of an epitaxial GaAs/AlAs multilayer grown on a Ge substrate and ͑2͒ 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 ϳ10 6 .
doi:10.1063/1.3455104 fatcat:asc4vv4wrrhthlnrnxnufuvkii