Sheet Resistance Reduction of Sputtered WS2 Film by Cl2 Plasma Treatment for Thermoelectric Devices

Reduction of electric power consumption is urgently required, therefore thermoelectric devices are attracting attention as a power regeneration method. The thermoelectric devices are environmentally friendly, because wasted heats are directly converted into electricity with the Seebeck effect. A Bi 2 Te 3 is currently a major thermoelectric material which has the Seebeck coefficient of about -7.56×10 [μV/K] [1] at room temperature, however higher thermoelectric performance is required for future highly efficient usage. Therefore, we selected a tungsten disulfide (WS 2 ) film, which is a kind of TMDC (Transition Metal Di-Chalcogenide) material with atomic 2D structure [2] [3] [4]. The WS 2 film has been reported to have the Seebeck coefficient of about 1.17×10 ³ [μV/K] [5] and is expected to be a new flexible semiconductor material. However, to maximize thermoelectric performance, the carrier density must be controlled as about 5 × 10 ¹⁹ [cm ^-3 ] [6].