Tilt investigation of In(Al,Ga)As metamorphic buffer layers on GaAs (001) substrate: A novel technique for tilt determination

Abstract

Crystallographic tilt and Surface topography of InGaAs and InAlAs based metamorphic buffer structures on GaAs (001) substrate grown by molecular beam epitaxy (MBE) under varying growth conditions have been investigated. Compressively strained metamorphic buffer layers show anisotropic strain relaxation. A novel tilt determination technique based on X-ray diffraction has been developed which can separate the effect of anisotropic strain. Tilt has been found to depend on compositional grading scheme, growth temperature and surface irregularities. Samples having random surfaces show smaller tilt than that of samples showing regular cross-hatch. At higher growth temperature, reduction of tilt has been observed and correlated with thermal activation of otherwise inactive slip systems at low temperature. At low temperature and also for continuously graded samples, reduction of tilt has been observed and correlated with the slower relaxation that provide the opportunity for all the slip systems to participate and compete.