A thin film efficient pn-junction thermoelectric device fabricated by self-align shadow mask

Event Date: January 23, 2020
Authors: G. Kogo, B. Xiao, S. Danquah, H. Lee, J. Niyogushima, K. Yarbrough, A. Candadai, A. Marconnet, S.K. Pradham, and M. Bahoura
Journal: Scientific Reports
Scientific Reports, vol. 10, 1067 (12 pages), 2020. DOI: 10.1038/s41598-020-57991-y

Large area highly crystalline MoS2 and WSthin films were successfully grown on different substrates using radio-frequency magnetron sputtering technique. Structural, morphological and thermoelectric transport properties of MoS2, and WS2thin films have been investigated systematically to fabricate high-efficient thermal energy harvesting devices. X-ray diffraction data revealed that crystallites of MoS2 and WS2 films are highly oriented in 002 plane with uniform grain size distribution confirmed through atomic force microscopy study. Surface roughness increases with substrate temperature and it plays a big role in electron and phonon scattering. Interestingly, MoS2 films also display low thermal conductivity at room temperature and strongly favors achievement of higher thermoelectric figure of merit value of up to 1.98. Raman spectroscopy data shows two distinct MoS2 vibrational modes at 380 cm−1 for E12g and 410 cm−1 for A1g. Thermoelectric transport studies further demonstrated that MoS2 films show p-type thermoelectric characteristics, while WS2 is an n-type material. We demonstrated high efficient pn-junction thermoelectric generator device for waste heat recovery and cooling applications.