| Computer simulations and experimental data have been used to study the organometallic vapor phase epitaxy (OMVPE) process. The specific case of GaAs growth from trimethylgallium and arsine has been considered. Mathematical models, based on solutions of the conservation of mass, momentum, energy and species equations, have been developed for this purpose. The models have included a rigorous thermal radiation analysis in the boundary conditions. Simulations of temperature isotherms and growth rates have shown a close match with experimental data over a wide range of operating conditions.;The problem of recirculation in conventional horizontal reactors was studied in detail as a function of reactor pressure, gas flow rate, susceptor slope, susceptor height and reactor height. Reactor design guidelines were developed for optimum methods of eliminating recirculation, based on their effect on large-area uniformity and deposition efficiency.;The parasitic reaction mechanism of triethylindium and arsine in the growth of GaInAs was studied. The reaction rate constants were determined and the composition of GaInAs predicted by the simulations were shown to match experimental data over a wide range of operating conditions.;A novel, close-spaced, inverted, stagnation flow, OMVPE reactor was designed and fabricated for large-area uniformity and high deposition efficiency. A rigorous computer model was developed to simulate the growth process in this reactor. A specially-designed, water-cooled, gas inlet nozzle was used to keep the nozzle temperature low enough to prevent reactants from pre-cracking, under all operating conditions. This was verified by temperature measurements and computer simulations.;GaAs epitaxial layers with good morphology, mobility, carrier concentration and minority carrier lifetime have been grown in the reactor. The effect of susceptor-nozzle distance, reactor pressure and gas flow rate, on large-area (2" diameter) uniformity and deposition efficiency, was studied. The thickness and doping distributions were determined by Fourier Transform Infrared Spectroscopy measurements. GaAs-on-sapphire experiments were shown to be an economical and valid method for studying large-area uniformity. Computer simulations were compared with the experimental data. Deposition efficiencies over 30% have been obtained in the present design. Further improvements in the reactor design have been suggested. |
