Rapid Annealing of Cu-In-Ga-Se Precursors by Electron Beam Irradiation Method.

Cu-In-Ga-Se precursors were prepared by RF- and DC-sputtering methods and then irradiated with an in-situ electron beam irradiation unit. Ternary (In,Ga)Se2 and binary CuSe targets were simultaneously used for preparation of precursors. The electron dose and irradiation time were kept constant at 300 seconds and 200 W of RF power, respectively, while intensities of accelerated electrons were varied from 2.5 to 4.5 keV. The thickness of all e-beam irradiated CuInGaSe2 (CIGS) films decreased from 1,250 nm to 470 nm. The crystalline properties of e-beam irradiated CIGS films were clearly shown on all samples and the highest intensity of (112) peak at 3.5 keV. The compositional ratio of Cu/(In + Ga) in the e-beam sample irradiated at 3.5 keV was coincident with that of the precursors. The degree of Ga content on the depth of the e-beam sample irradiated at 3.5 keV was uniformly distributed between the TCO/CdS layer and Mo back contact. Electron beam irradiation onto Cu-In-Ga-Se precursors as a rapid annealing method could be an excellent candidate for crystallization to the Cu(In,Ga)Se2 films.