Formation of Ge nanowires in oxidized silicon V-grooves by ion beam synthesis

The formation of Ge nanowires in V-grooves on (001)Si wafers has been studied experimentally as well as theoretically. The V-grooves were formed by anisotropic etching and subsequent oxidation of their surface. The implantation of 1 x 10(17) Ge+ cm(-2) at 70 keV into the oxide layer leads to an enrichment of Ge in the V-groove bottom. In this Ge-rich bottom region, subsequent annealing in N-2 atmosphere results in the formation of a nanowire by coalescence of Ge precipitates. Scanning transmission electron microscopy-energy dispersive X-ray analysis (STEM-EDX) investigations of as-implanted samples have confirmed the Ge accumulation at the V-groove bottom, whereas cross-sectional TEM studies of annealed samples prove the formation of a Ge nanowire. The formation mechanisms were studied theoretically by means of a continuum description of sputtering and kinetic 3D lattice Monte-Carlo simulations of phase separation. The preliminary results indicate the possibility of achieving nanowires being several nanometers wide by further growth optimizations. (C) 2001 Elsevier Science B.V. All rights reserved.