Structure of annealed nanoindentations in n- and p-doped (001)GaAs

We have studied the structure of annealed nanoindentations realized at room temperature (RT) on (001) GaAs having either n or p doping under a large range of loads F-m (between 0.5 and 50 mN). Transmission electron microscopy was used to observe systematically the nanoindentation structures. The lengths of the rosette arms were multiplied by a factor of two to three during the annealing process at 500 degrees C and were determined to vary with F-m, which could be modeled considering the two step thermomechanical history. While almost no anisotropy was observed before annealing (after indentation at RT), the [110] arms were observed to extend almost twice as long as the [10] ones in n-doped specimens after annealing. This anisotropy was much reduced in p-doped specimens. Furthermore, almost no partial dislocations were observed whereas they were obvious in n-doped specimens before annealing.