Development of an Industrial Fabrication Process for Next Generation, Thinner and Larger Crystalline Silicon (c-Si) Wafer-Based Solar Cells

The world's solar cell production has grown rapidly and steadily with an annual average of 30% over the last two decades. Single and micro-crystalline silicon solar cells have been the major reason for this production increase. In 2009, silicon-based solar cells comprised almost 90% of worldwide photovoltaic module shipments.;Reducing consumption of silicon through the use of thin wafers promises to significantly reduce the cost for the photovoltaic (PV) industry. Tradeoffs in efficiency, breakage and yield have slowed the industry's natural migration to thinner and larger wafers. Today's optimized solar cell structure screen-prints aluminum to the back side of the silicon wafer to create a back surface field and silver to the front side for front contact metallization. Because silicon and aluminum have different thermal expansion coefficients, wafer bowing occurs during the high temperature firing process for thinner wafers. As manufacturers move to larger size wafers, a great increase in resistive loss is caused by the high resistivity of the screen-printed silver front contact. New materials and processes to enable thinner and larger wafer usage have been investigated.;This thesis study demonstrates a one step, spin-on dopant (SOD) diffusion process that integrates the use of Boron as the back surface field as opposed to the industrial fabrication process of silicon based solar cells. Building from the spin-on dopant diffusion process results, a multi-step metallization process using nickel silicide, nickel, and copper will be presented to solve the high resistive loss problem with the current industrial technology.