TILTING OF LATTICE PLANES IN INP EPILAYERS GROWN ON MISCUT GAAS SUBSTRATES - THE EFFECT OF INITIAL GROWTH-CONDITIONS

The relative misorientation (tilt) between the epilayer and substrate (400) lattice planes of InP epilayers grown on (100) GaAs substrates misoriented towards the (110) plane was studied by high resolution X-ray diffraction. The epilayers were grown by gas-source molecular beam epitaxy. For the growth temperature of 490-500-degrees-C, the direction of the relative tilt was nearly coincident with the direction of the lattice plane tilting of the substrate, according to previous models. In contrary, when a buffer layer was deposited at a lower temperature of 400-450-degrees-C prior to growth, an azimuthal rotation of about 45-degrees was found between the directions of the relative tilt and the substrate lattice plane tilting. In order to explain the results, a temperature-dependent anisotropic nucleation model is proposed. The effect of misfit dislocations is also considered.