Diameter-controlled growth and impurity doping of silver colloid-seeded silicon microwires to nanowires for the realization of solar cell materials

Silicon (Si) microwires to nanowires were synthesized by chemical vapour deposition using silver (Ag) colloid catalyzed growth techniques. Control over diameter was achieved by varying the growth temperature while remaining far below the eutectic temperature of Ag colloids-Si system. Low-temperature growth of these nanowires demonstrates a vapour-solid-solid growth mechanism rather than a vapour-liquid-solid growth mechanism. Boron (B) acceptors and phosphorus (P) donor doping were carried out to make p-type and n-type Si wires. B local vibrational peaks and Fano broadening in optical phonon peaks of micro Raman scattering and electron spin resonance signals from the conduction electrons were used to demonstrate B and P atom doping respectively. These results will be important for future integration where Si wires can be combined as p-n junction for light harvesting material in next generation Si based solar cells.