Flow visualization studies for optimization of OMVPE reactor design

Abstract Gas flow visualization studies have been performed in a vertical reactor tube incorporating a rotating disk susceptor. Smoke particles of TiO 2 transported in a stream of He gas are illuminated by a sheet of laser light. This technique permits detailed observation of gas flow patterns. To study the influence of the method of gas injection, the gas was injected through (1) a vertical pipe inlet coaxial with the tube, (2) four inlets tangential to the tube and (3) a radial inlet above a porous plug. The method of injection was found to have a critical effect on vortex formation, which is minimized by using the porous plug. Disk rotation can be effective in creating a uniform boundary layer at the disk surface. When the susceptor is heated, the flow is strongly perturbed by thermally induced convection, which can be reduced by lowering the operating pressure.