Electrical conduction in the Si(111):B-(√3 × √3 )R30°/a-Si interface reconstruction

One-third of a monolayer of spatially ordered boron on (111)-oriented crystalline silicon is prepared in ultrahigh vacuum and then buried under a thin layer of amorphous silicon. This leaves a two-dimensional ({}3 ×{} {}3 ) boron layer in substitutional sites confined to a single monolayer on the crystalline side of the interface. We report electrical conductivity with a high p-type carrier density (>10¹⁴/cm²) in an ordered two-dimensional interface layer.