A novel reactor for large-area epitaxial solar cell materials

A novel vertical stagnation flow organometallic vapor phase epitaxy reactor was designed and fabricated for the growth of GaAs and AlGaAs for solar cell applications. The reactor had an inverted configuration to eliminate recirculation problems. The susceptor and gas inlet nozzle were closely spaced (about 1 cm) in order to achieve improvements in deposition efficiency, layer uniformity and abruptness of interfaces. A specially designed water-cooled inlet nozzle was used to maintain the nozzle surface at relatively low temperatures under all operating conditions. A computer model was formulated to study the various thermal processes in this reactor. The model used rigorous thermal boundary conditions which included thermal radiation effects. Simulated and experimental nozzle temperatures were compared for different susceptor temperatures, susceptor-nozzle distances, gas flow rates and reactor pressures. The maximum nozzle temperature was about 100 °C, which is sufficiently low to prevent premature decomposition of the reactants on its surface.