Effect of sputtering power on Cd/Zn atomic ratio and optical properties of Cu2ZnxCd1−xSnS4 thin films deposited by magnetron sputtering: An experimental and first-principle study

Highlights: • We deposited Cu₂Zn_xCd_1−xSnS₄ thin films using rf magnetron sputtering method. • It is found that Cd content in these films increases with increase of sputtering power. • The optical bandgap can be modulated from 1.45 to 1.32 eV as increasing sputtering power. • First-principles calculations indicate optical bandgap decreases with increasing Cd content. Cu₂Zn_xCd_1−xSnS₄ (CZCTS) thin films were deposited on soda-lime glass (SLG) substrates by rf magnetron sputtering. It is found that the Cd/Zn atomic ratio of kesterite CZCTS increases with the enhancement of sputtering power. The structural, surface morphology and optical properties of the CZCTS thin films deposited at different sputtering power were systemically investigated. The X-ray diffraction (XRD) measurements indicate that all CZCTS thin films are polycrystalline with kesterite structure and no impurity phase is observed. The variation of Cd/Zn atomic ratio in CZCTS results in the shift of the optical bandgap.