Modeling and simulation of microscopic defects in CIS-based solar cell thin film using silvaco TCAD

Reactively sputtered copper indium sulfide (CIS) chalcopyrite semiconductor has been actively studied as the potential absorber layer for solar cell thin film application. Using sputtering technique however could result in the formation of several types of defects for example microscopic defects. Microscopic defects are formed within the absorber layer due to the formation of pinholes after surface treatment process. Since the effects of the formation of pinholes in CIS-based thin film solar cell is not well understood yet, a detail study is therefore necessary. In this work, a solar cell model was developed and simulated using Silvaco TCAD tools. Cylindrical pinholes of various diameters and depths were created and analyzed. The simulation results predicted that the number and depth of the pinholes affect the performance of the CIS-based thin film solar cell. The variation of pinhole diameter however did not exhibit any significant effect. It was found that the increases in the number of the pinholes resulted in the increases of solar cell efficiency. The efficiency was predicted to be of around 17.5% when ten pinholes existed within the CIS layer. No significant effect was found as the diameter of the pinhole became wider. Deeper the pinhole depth into the layer however produced the solar cell efficiency of only 1.37%.