Microwave Photoconductance Spectrometer for Thin-Film Deposited Semiconductor Materials

Next-generation solar cells are being developed by researchers around the US and the world, but they lack a key component- measurement systems that can control the factories of tomorrow. A patent-pending machine was developed at NREL to do just that, and Tau is partnering with both NREL and University of Toledo to bring the machine to market. The technique uses a variable-wavelength light source and microwave reflectometer to measure the quality of thin-film semiconductor materials at a high rate- and keep up with the roll-to-roll deposition systems that are being developed in industry. In Phase I, Tau Science developed a compact prototype and found, during testing at NREL, that it met the goal of ~500x improvement in sensitivity relative to the original machine. This will be the starting point for our Phase II work, in which we will expand the capabilities into time-resolved and wavelength-resolved models that can provide even more information for process control in future PV factories. In Phase II, scientists from U. Toledo and NREL will generate samples to intentionally test the sensitivity of the technique to common processing problems, and will work with Tau Science to improve the machine until it is ready to deliver to the first US commercial customer in 2023.