Optimization of the properties of MOVPE-grown GaP epitaxial layers on GaP (1 1 1)B substrates

Abstract

Gallium phosphide (GaP) homoepitaxial layers are optimized by varying the growth temperature, growth rate and V/III ratio in a low-pressure metal organic vapour phase epitaxy (MOVPE) process. It is observed that we need high growth temperature, low growth rate and an optimum value of the V/III ratio in order to obtain a mirror finish surface morphology. The surface morphology is mirror finish for an epitaxial layer grown ⩾820 °C when viewed under a stereo-zoom microscope for a V/III ratio of about 100 or more. A sharp and intense excitonic photoluminescence (PL) feature and a fine structure associated with donor–acceptor pair recombination confirm a high optical quality of the grown layer, which is supported by high-resolution x-ray diffraction measurements. For silicon doping of GaP using silane in low-pressure MOVPE, our results confirm theoretical predictions available in the literature and the values of a distribution coefficient lie in a similar range known for other conventional semiconductors. This optimization provides high-quality GaP (1 1 1)B epilayers needed for the development of either nanostructure-based optoelectronic devices on transparent substrates or polarization-sensitive infrared photodetectors based on two-photon absorption.