Si field-effect transistor with doping dipole in buffer layer

An Si field-effect transistor with a doping dipole layer obtained by delta-n (δ_n) layer and delta-p (δ_p) layers in the buffer layer is proposed and fabricated. The dipole creates a large barrier between the channel and the buffer layer, and consequently more holes are confined in the upper undoped region (the channel layer) rather than around the δ_p layer by the influence of the transverse electric field coming from the δ_n barrier layer. This simple homoepitaxial grown Si structure exhibits an excellent property, i.e., not only high hole mobility (1350 cm² V^-1 s^-1) but also enhanced extrinsic transconductance (50 mS/mm), which is expected to provide an additional degree of freedom for Si-based device applications.