Backside etching process for enhancing the light trapping capacity and electrical properties of micromorph tandem solar cells

This research paper discusses a backside reactive ion etching (RIE) process to improve the light trapping properties of micromorph tandem solar cells. Reflection mostly occurs at the interface between the n-Μc-Si:H and silver electrode layers. We increase the amount of diffused reflection by introducing an etched rough interface. Absorption of diffused and scattered light is more efficient due to the increased light path length in the cells. Surface morphology was observed by atomic force microscopy (AFM). From this experiment the short circuit current density increased from 10.39 to 11.03 mA/cm2, measured and calculated by quantum efficiency results. As the etching time increases, the fill factor decreased due to increased recombination sites at the broader interface between the electrode and the n-Μc-Si:H layer. We applied hydrogen treatment in order to reduce this side effect. By adjusting this technique with a H₂ gas source, we could get a higher fill factor of 74.65% and energy conversion efficiency of 11.44%.