Interfaces between crystalline Si and amorphous B: Interfacial interactions and charge barriers

The recently found crystalline silicon-amorphous boron ($c$-Si/$a$-B) heterojunction has been successfully applied in the detection of short-wave UV photons. These detectors play a decisive role in the progress of nanoelectronics fabrication. The $c$-Si/$a$-B heterojunction could not be explained using the existing `instrumentarium' in semiconductor physics. We investigated the $c$-Si/$a$-B interfaces using ab initio molecular dynamics simulations. The simulations reveal atomic ordering of the $a$-B atoms adjacent to both the Si{0 0 1} and Si{1 1 1} substrates. Charge transfer occurs from the interfacial Si to B, thereby forming ${\mathrm{Si}}^{+}/{\mathrm{B}}^{\ensuremath{-}}$ charge barriers, which induce an electric field in the nearby regions. The obtained information here is helpful in furthering our understanding of the physics behind the $c$-Si/$a$-B junctions, as well as driving the development of a new `instrumentatrium' in solid state physics.