Temperature-dependent properties of Cu-doped ZnTe thin films deposited on ultra-thin glass substrates via RF magnetron sputtering
2025-01,
Nur Irwany Ahmad,
Ahmad Wafi Mahmood Zuhdi,
Camellia Doroody,
Yap Boon Kar,
Mohd Nazri Abd Rahman,
Kazi Sajedur Rahman,
Mohd Natashah Norizan,
Muhammad Najib Harif,
Tiong Sieh Kiong
This study investigates the viability of Cu-doped ZnTe as a potential back surface field (BSF) layer on flexible CdTe thin-film solar cells, examining its structural, morphological, optical, and electrical properties. ZnTe, 5%, and 8% Cu-doped ZnTe were deposited on ultra-thin glass (UTG) substrates using the radio frequency (RF) magnetron sputtering approach at varying substrate temperatures from room temperature to 300 °C. The finding reveals that the surface morphology significantly changes as the substrate temperature increases. Besides, incorporating Cu into ZnTe resulted in a denser and rougher surface, likely due to material densification and accelerated grain growth at higher temperatures. X-ray diffraction (XRD) analysis indicated that the crystallite size of the ZnTe and Cu-doped ZnTe increased with higher temperatures. Optical spectroscopy results demonstrated an increase in the optical band gap of ZnTe with increasing substrate temperature, while Cu-doping introduced a significant variability in the bandgap, particularly at different doping levels. In terms of electrical properties, ZnTe thin films exhibited carrier concentrations around 1014 cm−3. Conversely, the introduction of 5% and 8% Cu into ZnTe increased carrier concentrations, ranging from 1017 to 1020 cm−3, respectively, depending on substrate temperature and the amount of Cu concentration. Introducing Cu in the ZnTe structure may modify the characteristics of ZnTe thin films, potentially influencing its suitability as a BSF layer in CdTe solar cells by affecting its structural, optical, and electrical properties.