Absolute determination of the asymmetry of the in-plane deformation of GaAs (001)

Nanoindentation tests performed on GaAs (001) surfaces and on 4° misoriented GaAs (001) surfaces have led to the creation of anisotropic rosette arms lying along the 〈110〉 in-plane directions. One arm is always more elongated and constituted by perfect dislocations only while the shorter one shows in addition partial dislocations. Annealing of the deformed samples at 500 °C modifies the arrangement of the dislocations in the rosette arms but the asymmetry remains. Using a convergent beam electron diffraction method on plan views images obtained from indented (001) surfaces, we have determined the polarity of the samples. Experimental patterns were compared with simulated ones. The influences of several parameters were investigated and are discussed with particular attention addressed to the thickness of the samples. Before and after annealing, the longer rosette arm is constituted by α dislocations. The partial dislocations contained in the shorter rosette arm before annealing are of β type.