A.S. Sozykin, S.S. Strelchenko, Yu.P. Golovaty, M.A. Ladugin, A.A. Marmalyuk

Recently, as an alternative to zinc and magnesium as a doping impurity in the p-type compounds AIIIBV carbon has been proposed. Carbon is characterized by lower diffusion coefficient compared with other p-type impurities, it is not subject to «memory effect» and makes it possible to obtain high doping levels (>1020 см-3). Thanks to these properties, it now is increasingly increasing use in the manufacture of epitaxial structures, which require the creation of high-quality p-n junctions with a given level of concentration and providing accurate doping profiles needed to improve the parameters of the devices. Carbon tetrachloride (CCl4) is the preferred source of carbon for growing GaAs and AlGaAs epitaxial layers in MOCVD system. The main difficulties in using CCl4 is a high sensitivity to changes in process parameters AlGaAs in connection with the possibility of occurrence of a large number of additional chemical reactions in the gas phase. Therefore, a considerable amount of preliminary experimental studies with various parameters of growth. To solve the optimization problem of such a multifactorial process is commonly used thermodynamic models, which, however, for the doping of carbon halides so far not fully developed. At present work we have developed a thermodynamic model of growth and doping processes of GaAs and AlGaAs epitaxial layers grown in the system Ga(C2H5)3-Al(CH3)3-AsH3-CCl4-H2. The concentration of carbon was calculated in the approximation of regular solid solutions GaAs-GaC, AlAs-AlC. We have obtained the dependences of doping level of GaAs and AlGaAs epitaxial layers on main technological parameters of growth. The results of calculations were compared with experimental data.