PRESSURE AND TEMPERATURE-DEPENDENCE OF SILICON DOPING OF GAAS USING SI2H6 IN METALORGANIC CHEMICAL VAPOR-DEPOSITION

The doping of GaAs with disilane in a metalorganic chemical vapour deposition (MOCVD) process has been investigated at various input concentrations of disilane, total pressures and temperatures. The carrier concentration is linearly dependent on the input concentration of disilane. The temperature dependence of the incorporation process of silicon using disilane as a precursor changes as the total pressure varies. At a total pressure of 100 mbar the process is temperature independent in contrast to the behaviour at total pressures of 20 and 1000 mbar. So the doping process with disilane appears to depend on the total pressure. Using the concept of chemical boundary layer, the results are explained in terms of the different rate determining steps in the doping process as a function of different total pressures.