Boron monophosphide on Si and device applications

n- or p-type boron monophosphide (BP) with a forbidden energy gap of 2.0 eV was epitaxially grown on Si substrates using a B2H6-PH3-H2system, n-type (phosphorous) or p-type (boron) diffusion layers were also formed in the Si substrates. By combining the conductivity type of the BP, the diffusion layer and the Si substrate, several types of BP-Si junctions were realized. Two examples of applied devices were a wide gap window solar cell (η = 8.3%) and a wide gap emitter transistor (β = 16). The focus of our research projects on BP is the development of III-V compound semiconductor technology along the lines of the Si planar process.