Bonding of fluorine-implanted and annealed silicon

The effects of low temperature annealing on crystalline silicon samples, made amorphous by the ion-implantation of fluorine ions, has been studied using infrared spectroscopy. The implantation process is shown to result in a metastable state which, upon subsequent thermal annealing, converts to the well-characterized stretching and bending modes found in deposited silicon-fluorine films. Using arguments based on molecular orbital theory and model calculations, the metastable state is identified as a silicon-fluorine-silicon bridge.