Saturation of hole concentration in carbon-doped GaAs grown by metalorganic chemical vapor deposition

The behavior of hole concentration in carbon-doped GaAs grown by metalorganic chemical vapor deposition (MOCVD) is investigated using carbon tetrabromide (CBr4) as a C source. The hole concentration tends to saturate at higher CBr4 flow rates in the heavily doped region regardless of growth temperature, V/III ratio and Ga source. This tendency is found to be due to the saturation of C incorporation efficiency, not the deactivation of C accepters. It is also found that the saturation concentration, which is far lower than the value reported for metalorganic molecular beam epitaxy (MOMBE), is nearly independent of the growth conditions. These results suggest that an additional mechanism other than the solubility limit of carbon into GaAs must be considered to explain the saturation tendency of hole concentration in C-doped GaAs grown by MOCVD.