Mass Spectrometric Studies on Silicon Doping of OMYPE GaAs

The doping of OMVPE GaAs with silicon through use of disilane has been studied as a function of arsine concentration, alkylgalliums (trimethylgallium and triethylgallium), gas flow rate, reactor pressure, and temperature, using a low pressure reactor. Reaction products were analyzed by quadrupole mass spectroscopy (QMS). The apparent activation energy for disilane decomposition was investigated, and reactions concerning disilane were discussed. A new mechanism in which Si doping was accomplished by the SiH 3 AsH 2 decomposition on adsorption sites was then proposed. This mechanism can qualitatively explain dependences of doping on flow speed, growth temperature, and AsH 3 concentration. In addition, it also accounts for the difference in Si doping sites between OMVPE and MBE GaAs layers.