Fluidic assembly of hybrid MEMS: a GaAs-based microcantilever spin injector

A proof-of-concept fluidic assembly of a hybrid MEMS GaAs microcantilever spin injector is presented here. Instead of monolithically forming MEMS from pre-deposited layers, we fabricate a hybrid MEMS by assembling pre-fabricated parts. Sub-millimetre sized patches of GaAs having a thickness of 3 mu m are pre-fabricated, as is a metalized fused silica support layer. The GaAs patches are manipulated and assembled onto the silica support using capillary forces; the resultant hybrid MEMS comprises a GaAs microcantilever on a robust fused silica support. A novel ohmic contact is demonstrated by bonding a GaAs patch (p-type carbon doped to 1 X 1018 cm-3) onto the pre-metalized silica support layer prior to annealing; measurements revealed ohmic behaviour and a specific contact resistivity of ~10-5 Delta *W cm. Preliminary investigations show that, when contacting the cantilever against a metallic or magnetic surface, injected photocurrents as large as several tens of nA can be obtained, for which the spin polarization is equal to 16%.