Structure of nanoindentations in heavily n- and p-doped (0 0 1) GaAs

We have studied the nanoindentation structures achieved at room temperature (RT) on (0 0 1) GaAs with either n or p doping. Elastic–plastic nanoindentations were made over a wide range of loads (between 0.2 and 50 mN) at RT with a Berkovich indenter using two different orientations. Transmission electron microscopy was used to observe systematically the nanoindentation structures (central zone and rosette arms) and to investigate changes in dislocation activity. The mechanical response of both types of samples is relatively similar in terms of hardness, critical shear stress or pop-in load amplitude. In contrast, the indentation rosette structure appears to be sensitive to both doping and indenter orientation. Perfect dislocations show long screw segments only in n-doped specimens, a finding that is attributed to mobility effects. Moreover, p-doped specimens show no partial dislocations while n-doped specimens show partial dislocations in both rosette arms.