Optimizing thermoelectric power factor in magnetron sputtered Cu2Se thin films by varying substrate temperature and synergy of Cu/Se ratio

Abstract

Copper selenide (Cu2Se) is recognized as a p-type thermoelectric (TE) semiconductor known for its eco-friendliness, abundance in the earth's crust, and cost-effectiveness. Current research on Cu2Se primarily centers around its exceptional TE capabilities in bulk materials. However, two-dimensional thin films hold distinct advantages in TE micro- and nano-device development and applications. In the present study, a series of Cu2Se thin films were deposited on a glass substrate by employing radio frequency magnetron sputtering deposition by varying the substrate temperatures (Ts) from 50 °C to 400 °C with an interval of 50 °C. The impact of Ts role on the structural, microstructural, and electrical transport characteristics of Cu2Se thin films was investigated using the Grazing Incidence X-ray diffraction, High-Resolution transmission electron microscopy, Field Emission Scanning Electron Microscopy, and Seebeck analysis. The change in the Ts increased grain growth as observed from microstructure studies and improved electrical and transport characteristics. Notably, films deposited at Ts 350 °C exhibited a significant power factor of 16.8 μW/cmK2 at 450 °C, making them highly promising for TE applications.