Atomic hydrogen-assisted epitaxy for the reduction of composition modulation in InGaAsP

Abstract

<p>A miscibility gap exists in the InGaAsP/InP system of heterostructures such that a lateral composition modulation (LCM) occurs on the surface during growth resulting in the production of InAs-rich and GaP-rich regions within the layer. As a consequence, the important material properties relevant to optoelectronic device performance, such as the carrier mobility, luminescent properties and surface morphology, are less than optimum. Hence, this work investigates the influence of LCM on the structural and optical properties of InGaAsP quantum wells and thick layers grown by gas source molecular beam epitaxy on (100) InP substrates. Two novel growth techniques, argon plasma-assisted epitaxy and atomic hydrogen-assisted epitaxy, are developed to reduce the LCM. The reduction in LCM obtained with plasma-assisted epitaxy is explained in terms of the presence of atomic hydrogen within the argon plasma stream. A detailed atomistic model, including surface reconstruction effects based on reflection high energy electron diffraction observations, is developed to describe the surface-mediated processes that occur during growth in the presence of atomic hydrogen. A simple rate equation is used to understand the reduced LCM in terms of a decreased surface diffusion length of adatoms.</p>