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

Abstract

Large area highly crystalline MoS 2 and WS 2 thin films were successfully grown on different substrates using radio-frequency magnetron sputtering technique. Structural, morphological and thermoelectric transport properties of MoS 2, and WS 2 thin films have been investigated systematically to fabricate high-efficient thermal energy harvesting devices. X-ray diffraction data revealed that crystallites of MoS 2 and WS 2 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, MoS 2 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 MoS 2 vibrational modes at 380 cm −1 for E 1 2g and 410 cm −1 for A 1g. Thermoelectric transport studies further demonstrated that MoS 2 films show p-type thermoelectric characteristics, while WS 2 is an n-type material. We demonstrated high efficient pn-junction thermoelectric generator device for waste heat recovery and cooling applications.

Sheet Resistance Reduction of MoS₂ Film Using Sputtering and Chlorine Plasma Treatment Followed by Sulfur Vapor Annealing

“…As a method to avoid the unexpected difficulties and achieve large films, a sputtering method under ultra high vacuum (UHV) has been proposed as a physical vapor deposition (PVD) [14], [15]. For the Seebeck device in thermoelectric generator as an energy harvester, high efficiency of energy conversion was achieved in a sputtered MoS 2 film by low thermal conductivity [16]. However, sulfur atoms are easily out-diffused from the MoS 2 film during sputtering process, which cause high carrier density.…”

Si0.97Ge0.03 microelectronic thermoelectric generators with high power and voltage densities

“…This focus on complex high ZT materials is because a TEG’s ideal thermodynamic efficiency increases with the ZT of the materials used to form the thermopile 11 . Modern high ZT materials such as PbTe 12 , the BiSbTe system 13 , 14 , CuI 15 , Heusler alloys 16 , SnS 1− x Se x 17 , CsSnI 3− x Cl x 18 , Cu 2 Te:Ga 19 , and dichalcogenides 20 generally aim to achieve ZT ≈ 1 for T near 300 K.…”

2D Nanomaterials for Effective Energy Scavenging

“…Thin films give higher normalized α peak (peak value of the electrical conductivity) values [102]. Figure 7e is a schematic of a p-n junction-based thermoelectric generator (TEG), which is fabricated with RF (radio frequency) magnetron sputtering of MoS 2 along with the WS 2 thin films on the surface of a glass substrate, wherein the p-type or else n-type planar-patterned p-n junction is placed to the hot side of the device and the electrodes are at the cold side [103]. A clearer view of the MoS 2 and WS 2 films and the p-n junction of the fabricated TEG device are illustrated in Fig.…”

“…[ 102 ], © 2019 Nature; e , f , g , h , i Ref. [ 103 ], © 2020 Nature; j , k , l Ref. [ 87 ], © 2019 Nature …”

“…7 g, h, respectively, displaying the start of increasing current at the turn-on voltage ( V on ) of 0.2 V. In addition, the power factor of the MoS 2 -based TEG is shown in Fig. 7 i from where the highest calculated power factor is 1.15 × 10 –3 W m −1 K −2 and is achieved at 370 K [ 103 ].…”