Mechanical properties of bismuth implanted amorphous Ge film

Mechanical properties of Bi ion implanted a-Ge film were studied by dynamic microhardness tests and compared to those of unimplanted a-Ge film, 400 nm thick films were evaporated in units of 30 nm thick layers and bombarded w ith Bi ions at 60 keV energy and 2 mu A/cm(2) current, Cyclic load-unload i ndentation tests and indentation creep tests were performed to determine th e hardness and ductility of the ion implanted and unimplanted specimens, re spectively, The brittleness of the materials was characterised by scanning electron microscopic observation of crack formation around the Vickers inde ntations. The dynamic hardness was much larger, the ductility lower, the cr ack formation was significantly larger in the case of the unimplanted than in the ion bombarded specimens. The observed differences in the mechanical properties indicate structural differences between the two types of a-Ge ar e in agreement with the earlier reported formation of a new amorphous phase of Ge induced by ion implantation (G. Peto, J, Kanski, U. Sodervall, Phys, Lett, 124 (1987) 510 [6]). (C) 1999 Published by Elsevier Science B.V. All rights reserved.