###### Abstract  
Improvement in crystallinity was investigated by compensating for stoichiometric deviations of non-selenization processed Cu\({}_{0.9}\)In\({}_{0.7}\)Ga\({}_{0.3}\)Se\({}_{2}\) (CIGS) thin films due to highly volatile Se by co-sputtering them with Te followed by rapid thermal annealing. The prepared CIGS:Te thin films did not show any linear correlation between the compositional ratio and the co-sputtering time of Te; however, the deviation parameter (\(\Delta\)s) from the stoichiometry and normalized stoichiometric deviations of Se + Te and In + Ga were largely consistent with the behavior of thin-film properties. The proposed method provides better crystallinity with a large grain size, clear grain boundaries, and low microstrain and dislocation density, resulting in a large volume of the unit cell. The CIGS:Te thin films used as absorbers show improved optical properties compared to the conventional CIGS thin films, with \(E_{g}\) = 1.548 eV. These results can advance the low-cost commercialization of the enhanced-efficiency CIGS:Te thin films without the selenization process.  
CIGS:Te thin films; non-selenization; co-sputtering; Cu\({}_{0.9}\)In\({}_{0.7}\)Ga\({}_{0.3}\)Se\({}_{2}\) (CIGS) target; Te target; rapid thermal annealing; RTA Article  
Cu(In,Ga)Se\({}_{2}\):Te Thin Films for Stoichiometric Compensation by Using Co-Sputtering and Rapid Thermal Annealing +
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Footnote †: This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.  
allowing it to participate in _p-d_ and _s-p_ transitions for increasing the uncertainties in band structure with a lower barrier height for p-n junction formation [18; 19]. Although this gives a corresponding loss of photocurrent, this can enhance the open-circuit voltage (\(V_{\alpha}\)) by increasing the band gap of the absorber layer by compensating for Se vacancies [18; 20]. Magnetron sputtering has the advantages of excellent composition transfer, superior adhesion of thin films, straightforward control of the deposition rate, uniform surface morphology, possibility of large-area deposition, and low-cost and full-vacuum equipment [21; 22]. Moreover, the co-sputtering process can be performed as a one-step process with control over the composition of the films without the use of toxic or explosive chemicals or high-cost equipment for the selenization process. The focus of this study is to examine the effect of Te incorporated into the space charge region of CIGS thin films prepared using radio frequency (RF) magnetron co-sputtering equipment with Cu\({}_{0.9}\)In\({}_{0.7}\)Ga\({}_{0.3}\)Se\({}_{2}\) and Te targets. A series of Te-doped CIGS (CIGS:Te) thin films were fabricated with different Te contents at a constant total thickness, which was controlled by the deposition time for the Te target. Then, all the precursors were annealed by using a rapid thermal annealing (RTA) system to prevent the volatilization of Se and Te-nonhomogeneity.