Epitaxial aluminium nitride on patterned silicon

Abstract

Aluminium Nitride (AlN) layers have been grown by molecular beam epitaxy (MBE) on Si(1 1 1) substrates in order to fabricate cantilevers. Two different approaches are compared, the first one by growing on planar wafers and the second one by growing on pre-patterned Si wafers. The surface and structural qualities were assessed by reflection high energy electron diffraction (RHEED) and scanning electron microscopy (SEM). Resonance frequencies and quality coefficients Q of our microstructures were studied by laser vibrometry. AlN cantilevers exhibiting very similar properties are demonstrated for both fabrication routes. Avoiding the difficult task of AlN etching, the growth on patterned Si substrates looks promising.