Please choose your delivery country and your customer group
Zone-melting recrystallization (ZMR) of Si on SiO sub 2 is investigated to determine if this process can be adpated to produce material configurations suitable for low-cost, high-efficiency photovoltaic cells. Fundamental recrystallization mechanisms, crystallographic characteristics and electrical properties are studied. Novel means of controlling crystallographic properties have been developed, including: hourglass, vertical-constriction, entrainment, and orientation-filtering techniques. EBIC studies indicated enhanced dopant diffusion along grain boundaries and subboundaries, and showed that the diffusion length of minority carriers is approx. 100 mu m. DLTS studies showed that ZMR films do not contain deep levels associated with impurities, and have interface-state densities comparable to IC-grade Si wafers. A (100) crystallographic texture can be achieved in 50 mu m-thick ZMR Si films using the vertical-constriction technique. Such films can provide a double pass of incident light and should be suitable for high-efficiency photovoltaic cells. Both two-sided and back-contact cells have been fabricated. We intend to develop a process in which thick Si films are recrystallized directly on the windows of photovoltaic modules. This should lead to considerable economy. (ERA citation 08:053771)