Problem statement: For low cost manufacturing of high efficiency solar cells and solar modules, manufacturers are ever looking for effective tools to measure the problematic defects and performance variations in their critical processes. Approach to addressing the problem: The light, or laser, beam induced current (LBIC) technique has been used in the laboratory to produce detailed images of the opto-electronic performance of photovoltaic devices. These images locate defects, and with analysis of the signals, can provide measurements of properties such as diffusion length, shunt resistance, surface recombination, etc. An in-line instrument providing such measurements would be an extremely useful process control tool. We are proposing an In-line LBIC machine that would be capable of producing these types of process control measurements within solar cell and solar module manufacturing cycle times. By integrating four lasers into a compact optics head, and scanning it in discrete paths over a module or cell, a large number of well-distributed data points can be acquired. Analyzing and reducing these multiple wavelength data points into a few well-chosen figures of merit, in near real time, would provide the manufacturing line with essential measurements of process variability.
Benefits: Near real-time measurements will reduce process variability and enable increased module efficiency and reduced manufacturing cost. In addition manufacturing lines will ramp up more quickly and R & amp;D can be more effective.
