Relaxation of residual stress-controlled thermopower factor in transparent-flexible Ti-doped ZnO thin films. Issue 2 (15th January 2022)

• Record Type: Journal Article
• Authors: Truong, Dai Cao; Thaowonkaew, Somporn; Muthitamongkol, Pennapa; Horprathum, Mati; Kumar, Manish; Le, Thu Bao Nguyen; Pham, Anh Tuan Thanh; Seetawan, Tosawat; Vora-ud, Athorn; Phan, Thang Bach
• Is Part Of: Ceramics international. Volume 48:Issue 2(2022)
• Page Start: 2605
• Page End: 2613
• Publication Date: 2022-01-15
• Subjects: Ti-doped ZnO thin Films -- Flexible-transparent thermoelectric -- Residual stress -- Thermopower factor -- Post-thermal treatment; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.10.043
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: Transparent-flexible thermoelectric materials are attractive for future small-sized consumer electronics, the internet of things, and wearable devices. The microstructural evolution and subsequent thermoelectric properties of Ti 1%.at-doped ZnO thin films, grown on polyimide flexible substrates, are presented. The thin films were grown using radio frequency a magnetron sputtering method followed by annealing for 60 min at temperatures of 200–400 °C under vacuum atmosphere. Post-annealed films demonstrate a hexagonal Wurtize structure. It is found that the annealing helped to relax residual stresses in the thin films, subsequently leading to enhanced charge concentration, carrier mobility, mean free path, and density-of-states effective mass. The thin film, annealed at 300 °C, illustrates the highest power factor of the films measured at room temperature at 19.10 μW m −1 K −2 . Further increases in the annealing temperature suggest Ti 2+ diffuses into the ZnO lattice and in turn disturbs the crystalline structure; this results in a reduction of the power factor to 9.32 μW m −1 K −2 at an annealing temperature of 350 °C.