Polarity influence on the nanoindentation response of GaAs

We have studied the polarity influence in the nanoindentation response of GaAs{111}. The nanoindentations were made under a large range of loads (Fmax between 0.2 mN and 50 mN) at room temperature on {111} faces of A (Ga) or B (As) character. Transmission electron microscopy (TEM) was used to observe the nanoindentation structures generated at the two polar surfaces. The indentation rosettes possess a 3-fold symmetry with arms developed along the 〈110〉 directions parallel to the surface. For a A-polar face, the rosette arms are constituted by two arms a long arm (LA, α dislocations) and a short arm (SA, β dislocations) while at the B surface only the LA (β dislocations) are formed. Furthermore, only for an A polar face microtwinning was observed to form and this is found to be in good agreement with previous observations of anisotropic microtwinning at GaAs(001) surfaces. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)