Cold compaction of silicon powders without a binding agent

We report on a novel process for the fabrication of silicon compacts, from low-cost powders, without the need for a binding agent and which avoids the inclusion of native oxides and high-temperature processing. Various types and grades of silicon powder are conditioned to produce particulates with a hydrogen-terminated surface before subjecting to uniaxial mechanical compression, at pressures between 100 MPa and 1000 MPa, at room temperature. The evolution of silane gas on initial exposure of the compacts to air indicates breaking of weak silicon-hydrogen bonds and silicon-silicon bonds during compaction. The silicon compacts have an inherent macro-porosity, with densities > 75% of solid silicon, depending on the size range of compacted particles. Enhancement in direct silicon-silicon bonding results in electrical continuity of compacted samples which are also chemically stable in HE (c) 2006 Elsevier B.V. All rights reserved.