Initial stages of mocvd growth of gallium nitride using a multi-step growth approach

摘要

A multiplayer buffer layer approach to GaN growth has been developed in which the thermal desorption and mass transport of low temperature buffer layer are minimized by deposition of successive layers at increased temperatues.High quality GaN with featureless depositionof successive layers at increased temperatures.high quality GaN with featureless surface morphology has been grown on (0001) sapphire substrate by metalorganic chemical vapor deposition using this multilayer buffer layer approach.The lateral growth and coalescence of truncated 3D islands (TTls) nucleated on low temperature buffer layers at the initial stage of overlayer growth is affected by the thickness of the final buffer layer on which nucleation of TTls takes place. The effect of the thickness of this buffer layer on the quality of GaN is studied by using scanning electron microscopy, can der Pauw geometry Hall measurements and cathodoluminescence and an optimum value of 400 A is obtained.