Anisotropy and polarity of hardness in III-V and group IV semiconductors

Conference item

‘Hardness anisotropy’ is the variation of measured hardness with orientation of a low-symmetry indenter on a particular crystallographic plane. 'Hardness polarity' is the difference in hardness, measured using a high-symmetry indenter, between (hkl) and (hl:l) planes in non- centrosymmetric crystals. Results are presented for Ge, GaAs and InSb, for the temperature range 20-400 °C. Ge, GaAs and InSb all show hardness anisotropy on {001} faces, with indenter long-axis alignment along <100> giving the highest hardness value; in addition, InSb and GaAs show anisotropy between <110> and <110> directions. Both InSb and GaAs exhibit hardness polarity on {111} faces. A new model of flow patterns under and around contact zones in hard crystals has been developed, based on resolution of realistic elastic stress fields onto available slip systems. Slip systems fall generally into three categories: (a) those that converge beneath the indenter (high work-hardening rate); (b) those that diverge with increasing penetration into the crystal (low work-hardening rate); (c) those with slip direction parallel to the indenter surface (‘rosette’ slip). The orientation and work-hardening characteristics of these different sets of activated slip systems for different orientations of the indenter (and, in III-V compounds, the different mobilities of alpha and beta dislocations) accurately predict the observed slip and fracture patterns. The hardness polarity and anisotropy behaviour can then be explained in terms of the extent of slip on systems with a low work-hardening rate.

Authors: Warren, P; Roberts, S; Hirsch, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Institute of Physics
• Host title: 5th International Symposium on Structure and Properties of Dislocations in Semiconductors
• Journal: 5th International Symposium on Structure and Properties of Dislocations in Semiconductors
• Publication date: 1986-03-01
• ISBN: 9780854980604
• Keywords: SBTMR