Effect of Reduced Cu(InGa)(SeS)$_{bm 2}$ Thickness Using Three-Step H$_{bm 2}$Se/Ar/H $_{bm 2}$S Reaction of Cu

摘要

Cu(In,Ga)(Se,S)$_{bm 2}$ (CIGSS) absorbers with thicknesses from 1.9 to 0.25 μm have been grown using a three-step selenization/Ar-anneal/sulfization reaction of Cu–In–Ga metal precursors. Material characterization revealed changes in orientation, apparent grain size, and formation of voids at the Mo/CIGSS interface with reduced thickness. Even with absorber thickness decreased to 0.25 μm and lateral compositional nonuniformity, $V_{bf OC}$ and fill factor were nearly sustained, while $J_{bf SC}$ decreased due to incomplete absorption. With the 0.25-μm-thick absorber layer, an efficiency of 9.1% (without AR coating) with $V_{bf OC}$ = 612 mV, $J_{bf SC}$ = 21.0 mA/cm $^{bm 2}$, and FF = 71.1% was obtained.