Plastic deformation of GaAs at low temperatures

Intrinsic GaAs single crystals were deformed under hydrostatic pressure at temperatures down to 130K. Slip lines indicate that, below 300 K, deformation occurs by 1/2 (101)(111) slip with frequent cross-slip. Above 300 K the crystal is so brittle that no slip lines are observed and the critical resolved shear stress t_cfalls steeply with increasing temperature. Below 300 K the temperature dependence of t_cis weak, resulting in a hump in the t_c-T curve at about 300 K, as found in InP at 420 K. In this region the activation volume is several b³b being the length of the Burgers vector, and the activation energy is about 35kT. Transmission electron microscopy of specimens deformed at low temperatures reveals long screw dislocations, which are narrowly or not at all dissociated. Semiquantitative analysis indicates that, at low temperatures, plastic deformation occurs by kink pair formation of non-dissociated shuffle screw dislocations.