Characterization of Recrystallized Sintered Silicon Substrates for Photovoltaic's Solar Cells
Résumé
In this work, we describe a new process of fabrication of low-cost silicon wafers which are produced by sintering silicon powder followed by a Zone Melting Recrystallization (ZMR) step. The influence of the ZMR step on the physical and chemical characteristics of the substrate is reported. The evolution of the impurities content along the different steps of the substrate process was studied. In addition to the increase of the grain size and improved crystalline quality, the ZMR step allowed reducing the total impurities and especially the oxygen content already present in sintered wafer. Furthermore the ZMR improved drastically the value of the minority charge carrier lifetime resulting from impurities reduction and the crystal growth in the sintered substrate. The recrystallized sintered wafers showed a good majority carrier mobility of 245 cm2 V-1 s-1 and a doping level of 5x1016 atm cm-3. The efficiency of 8.9% obtained with the recrystallized sintered wafer, using the simplified cell process, is very encouraging.