Abstract: Thin films of single crystal, cubic boron nitride phosphide are provided on, and in crystallographic registry with, an underlying silicon substrate which is oriented along a single crystallographic axis. The cubic boron nitride phosphide films are deposited using laser ablation methods. The boron nitride phosphide film has a crystallographic lattice constant which can be systematically varied depending upon the desired film composition and processing parameters. Preferably, the target, and accordingly the resulting thin film composition, is characterized by a chemical formula of BN.sub.(1-x) P.sub.(x) where x is about 0.23. This particular composition results in a crystallographic lattice constant essentially equal to the single crystal silicon substrate. The film may also have the formula BN1-xPx where x<0.ltoreq.1.

Abstract: The invention is predicated upon the discovery by applicants that exposure of a Ge surface to arsenic produces a drastic change in the step structure of the Ge surface. Subsequent exposure to Ga and growth of GaAs produces three-dimensional growth and a high threading dislocation density at the GaAs/Ge interface. However exposure of the Ge surface to Ga does not substantially change the Ge step structure, and subsequent growth of GaAs is two-dimensional with little increase in threading dislocation density. Thus a high quality semiconductor heterostructure of gallium arsenide on germanium can be made by exposing a germanium surface in an environment substantially free of arsenic, depositing a layer of gallium on the surface and then growing a layer of gallium arsenide. The improved method can be employed to make a variety of optoelectronic devices such as light-emitting diodes.