Carbon tetrabromide (CBr4) has been used as a source of p-type dopant in GaAs (GaAs:C) grown by solid source molecular beam epitaxy (SSMBE). The stability and sustainability of the CBr4 flux were investigated in terms of the leak valve position and CBr4 cylinder temperature. It is found that stable and sustainable CBr4 flux ranging from similar to2.0 x 10(-8) to similar to1 x 10(-6) Torr can be obtained by regulating the leak valve opening position within cylinder temperature of 2-20degreesC. The hole concentration in GaAs increases linearly following increase in CBr4 flux UP to 2.6 x 10(-7) Torr, at which the hole concentration is the highest at 1.86 x 10(20) cm(-3). Thereafter, the hole concentration decreases due to formation of electrically inactive C-C pairs. The memory effect in GaAs from possible background carbon doping was found to be at an acceptably low level of similar to10(15) cm(-3) hole concentration, indicating the viability of CBr4 usage in SSMBE for p-type doping. (C) 2003 Elsevier Science B.V. All rights reserved.