Improvement of Silicon Solar Cell Substrates by Wet-Chemical Oxidation Studied by Surface Photovoltage Measurements

The deposition of thin and ultra-thin layers requires extremely clean, smooth and defect-free Silicon (Si) substrate surfaces as starting point. The preparation-induced surface micro-roughness and surface coverage of the substrates often affect the initial layer growth, the morphology or the adhesion of deposited layers. Si device fabrication includes multiple wet cleaning and etching steps involving different oxidizing and etching solutions, which modify the surface electronic properties according to fixed charges and defect states present on the surface. Depending on the details of the device structure, surface conditioning methods have to be carefully optimized to achieve the desired electronic interface properties.