Cu(In,Ga)Se2 layers from selenization of spray deposited nanoparticles

Spray deposited nanoparticle derived Cu(In,Ga)Se-2 (CIGS) layers were selenized with a two-zone RTP furnace in order to get a solar cell applicable dense CIGS absorber layer. Effects of various selenization parameters including Se evaporation temperature, flow rate of carrier gas and substrate temperature on the growth of CIGS nanoparticles were investigated. The experimental results revealed that higher amount of Se vapor generated and transported to CIGS nanoparticles, i.e., higher temperature of Se evaporation and/or higher flow rate of carrier gas, resulted in the larger CIGS grains. High substrate temperature also enhanced the growth of individual nanoparticles. However, direct contact of Se vapor with bare Mo surface through the large numbers of pores in the layer gave rise to a formation of very thick MoSe2 layer which at times caused the CIGS/MoSe2/Mo layers to peel off the glass substrate, presumably due to the significant molar volume difference between Mo and MoSe2.