Comparative Study of Top Contact Materials in CZTS Based Schottky Diodes

CZTS-based Schottky devices often suffer from performance variability due to inappropriate selection of metal contacts, which influences barrier height formation and charge conduction. This paper presents a detailed comparison study of four metals including copper, silver, aluminum, and titanium as Schottky contact materials on spray deposited CZTS layers under the identical fabrication conditions. The fabricated Schottky diodes were evaluated by measuring their current–voltage characteristics to determine their key electrical properties. Barrier heights range in the following order: Cu (0.6993 eV) < Ag (0.7125 eV) < Al (0.7501 eV) < Ti (0.8123 eV). The ideality factor was determined to be between 1.31 and 1.9. Among these, titanium has the highest barrier height and better rectifying properties, while silver exhibits quasi-ohmic behavior owing to a lower effective barrier height. The study establishes a clear correlation between metal work function, interfacial effects, and diode performance, providing guidance for optimal contact selection in CZTS-based optoelectronic devices.