Production of silicon fine particles from recovered silicon wafers

Silicon wafer, the semiconductor material in silicon-based solar cells, is the most energy-consumed material which carries around sixty percent of the cell cost. Degraded or damaged silicon-based solar cells have been forgone unfavorably. To take advantage of that free silicon resource, this work has modified the recovered silicon wafers into fine particles. The experiment started with decreasing the size of the wafers into millimeters using a pestle-mortar set, then ball-milled at 400 rpm for 1 h with 5 mm balls and a 10:1 ball-to-powder ratio. The obtained powder was then subjected to hydrogen fluoride (HF) acid treatment to remove the silicon oxide followed by washing with DI water and drying in a modified vacuum set. As a result, silicon fine particles with an average size of not more than 120 nm have been obtained with oxygen concentrations of 7.65% and 2.4% before and after acid treatment, respectively. The XRD result shows the obtained powder was crystalline silicon which has the potential to be used as a semiconductor material in various applications.