ANALYSIS OF MOCVD OF GAAS ON PATTERNED SUBSTRATES

A single species diffusion model is used to simulate the localized growth of GaAs by metalorganic chemical vapor deposition (MOCVD) with trimethylgallium (TMG) and arsine over patterned substrates. The effects induced by the surface topology of nonplanar substrates are investigated first with good agreement obtained between the model and experimental results for deposition within a trench. Next, a coupled volume and surface diffusion model is presented to simulate selective growth within a stripe pattern defined on a masked substrate. A parametric study is accomplished in order to determine the impact of the various mask and system properties upon the transport of TMG to the window area. Direct diffusion from the gas phase is shown to be the predominant mechanism of transport with the mask sticking coefficient controlling the extent to which surface diffusion contributes. The mask coverage and total system pressure exhibit the greatest effect on gas phase diffusion while surface diffusion remains relatively negligible in the parameter space explored. The model shows good agreement with published experimental results.