High mobility two-dimensional electron system on hydrogen-passivated silicon(111) surfaces

We have fabricated and characterized a field-effect transistor in which an electric field is applied through an encapsulated vacuum cavity and induces a two-dimensional electron system on a hydrogen-passivated Si(111) surface. This vacuum cavity preserves the ambient sensitive surface and is created via room temperature contact bonding of two Si substrates. Hall measurements are made on the H–Si(111) surface prepared in aqueous ammonium fluoride solution. We obtain electron densities up to 6.5×1011cm−2 and peak mobilities of ∼8000cm2∕Vs at 4.2K.