A GaAs MEMS for AFM and spin injection

Abstract

We investigate the mechanical and electrical properties of tip-less, GaAs micro-cantilevers on silica supports that are fabricated using a novel assembly approach. The resulting device is compatible with an atomic force microscope (AFM) and takes advantage of the electronic and optical properties of GaAs as well as the mechanical properties of silica. Mechanically, their resonant frequency and quality factor, as well as their AFM imaging capabilities (lateral resolution ∼10–20nm), are comparable to commercial silicon cantilevers despite the absence of micromachined tip. In the same AFM-like configuration, they can also function as novel spin-polarized electron injectors under excitation by a circularly polarized laser from the rear. Surface nitridation of the cantilever and deposition of a hydrophobic thin polymer film on the sample surface are found to stabilize the injected photocurrent, making them potentially useful for a variety of fundamental and applied investigations in atmosphere.