Study of silicon incorporation from SiH₄ in GaAs layers grown by metalorganic vapor phase epitaxy using tertiarybutylarsine

The incorporation of silicon from SiH₄ into GaAs grown using tertiarybutylarsine (t-C₄H₉AsH₂ or TBAs) as the group V source has been investigated. The dependence of silicon incorporation on growth conditions was used to evaluate the role of gas phase and surface chemistry in the doping process. The use of TBAs results in a greater SiH₄ doping efficiency and weaker dependence on growth temperature than is typically observed with AsH₃. The doping is insensitive to gas residence time with AsH₃ and TBAs, indicating that the process is limited by heterogeneous chemistry in both cases. AsH₃ addition to layers grown at a constant TBAs/TMGa ratio results in a rapid decrease in Si incorporation. A surface kinetic-limited process is proposed to describe this behaviour. The influence of TBAs on SiH₄ doping chemistry was also found to improve the doping uniformity of GaAs films grown in our metalorganic vapor phase epitaxy (MOVPE) reactor.