Liquid phase epitaxy of silicon from tin alloys at low temperature

For low-cost solar cells, silicon thin film growth using low temperature liquid phase epitaxy (LPE) technique can be a good candidate. At such temperature (700-800 °C) the main difficulties are the removal of native silicon oxide and the low solubility of silicon in solvents. In this work we study the use of different liquid solvents tin, indium, lead and their alloys at 800 °C. In addition a small amount of aluminum is incorporated in the melt to prepare an oxide free surface. Better morphology and higher thickness were observed when using pure Sn or Sn-rich solvent in the binary Sn-In alloy. A 17 μm thick layer was obtained at 800 °C. This thickness is sufficient to realize thin film solar cell with adequate optical confinement. To improve this thickness, addition of a metal presenting high Si solubility is required.