n order to determine optical bandgap, the Tauc relation-ship is used as follows [24]:ahv=Ahv−Egn,3whereais absorption coefficienta=−107lnT/t,Aisa constant,his Planck’s constant,vis photon frequency,Egis optical bandgap, andnis 1/2 for allowed direct semi-conductor bandgap. The bandgap energy of ZnS thinfilmwas estimated by plottingahv2againsthvas in Figure 10;