SolR® is an in-line, contactless, fast-probing white-light reflectance measurement system. It is capable of measuring the properties and thickness of all layers throughout thin-film solar cell manufacturing processes, including transparent conducting oxide (TCO) and absorber and buffer layers. SolR can be adapted to any thin-film deposition system. It is designed to be integrated into typical in-line and roll-to-roll processes and is applicable to all major types of substrates and PV cell designs.
The SolR® system monitors the spectra of light reflected from the coated substrates as they pass the measurement position. The position and number of interference fringes in the measured spectra are automatically analyzed and fitted to determine the film thickness on-line. By measuring the reflectance after each deposition step, the thickness of each layer can be determined with high precision.
While TCO and CdS film thicknesses are detected with a spectrometer operating in the visible to near-infrared spectral range (500–1000 nm), a determination of the film thickness of the absorber layer requires an infrared reflectance measurement, as these materials are designed to completely absorb visible light. The thickness measurement accuracy is typically 1–2 %. LayTec has built upon its extensive expertise in fitting optical data and accurately measuring optical properties (n and k values) in multi-layer processes to create the most precise automated thickness analysis available for thin-film PV.