H$_{2}$-diluted precursors for GaAs doping in chemical beam epitaxy

A wide range of n- and p-type doping levels in GaAs layers grown by chemical beam epitaxy is achieved using H$_{2}$-diluted DTBSi and CBr$_{4}$ as gas precursors for Si and C. We show that the doping level can be varied by modifying either the concentration or the flux of the diluted precursor. Specifically, we demonstrate carrier concentrations of 6$\times$10$^{17}$-1.2$\times$10$^{19}$ cm$^{-3}$ for Si, and 9$\times$10$^{16}$-3.7$\times$10$^{20}$ cm$^{-3}$ for C, as determined by Hall effect measurements. The incorporation of Si and C as a function of the flux of the corresponding diluted precursor is found to follow, respectively, a first and a fourth order power law. The dependence of the electron and hole mobility values on the carrier concentration as well as the analysis of the layers by low-temperature (12 K) photoluminescence spectroscopy indicate that the use of H$_{2}$ for diluting DTBSi or CBr$_{4}$ has no effect on the electrical and optical properties of GaAs.