Large grain polycrystalline silicon from rice husk

Abstract

Rice-husk may constitute a viable alternative raw material for production of solar grade silicon. Powdered silicon obtained by Mg reduction of rice-husk ash was subjected to melting and directional solidification resulting in large-grain (3 × 8 mm²) polycrystalline silicon ingots. The material was found to be p type with resistivity 0.1- 0.3Ω cm within the grains. The hole concentration was 8 × 10¹⁷ cm^-3 and mobility 69 cm²V^-1S^-1 as found from Hall effect studies. Steady-state photoconductivity indicated electron life-times greater than 10^-6 s which is promising for photovoltaic applications. The conductivity activation energy of 0.045 eV showed that B was the active impurity.