The deformation of Si‐doped GaAs single crystals with a carrier concentration of 1018cm−3was investigated by determining the stress/strain relationships for &agr; and &bgr; bending at 500 °C. Marked differences were found between the &agr; and &bgr; deformation curves. Using Gilman and Johnston’s model for dislocation multiplication and combining it with a linear relationship between the dislocation velocity and applied stress, a theoretical model was developed to explain the above‐mentioned differences in terms of dislocation mobilities &mgr;, dislocation multiplication factorsC, activation stresses &tgr;a, and the initial densities of dislocation sources &rgr;0. Applying a numerical curve fitting procedure to the experimental curves, these parameters were found to have the following values for &agr; and &bgr; bending, respectively: &mgr;&agr;=8.5×10−12and &mgr;&bgr;=3.8×10−12cm3 dyn−1 sec−1;C&agr;=89 andC&bgr;=130 cm−1; &tgr;a&agr;=2.11×108and &tgr;a&bgr;=2.7×108dyn cm−2; &rgr;0&agr;=9×105and &rgr;0&bgr;=4.5×102cm−2.