Optimization of electrical performance of Cu(In,Ga)Se2 thin film solar cells sputtered from quaternary targets

Utilizing a quaternary target to sputter Cu(In,Ga)Se₂ (CIGS) yields films which are dense, polycrystalline and highly oriented. Devices fabricated from these films exhibited efficiencies >10%. In this paper, we study the electrical characteristics of these devices, including current-voltage (I-V), external quantum efficiency (EQE) and sheet and contact resistances measured by the transfer length method, to improve their overall performance. The effect of edge termination by different techniques is reviewed to investigate perimeter effects and edge defects. It was found in these particular devices that mechanical scribing of device areas contributed to both edge and bulk shunt effects. We discuss the extent of these effects in the context of increasing device efficiency through the optimization of edge termination.