Low-Frequency Noise in Transition Metal Dichalcogenides Field-Effect Transistor

• Main Authors: Wang, Ji-Wun, 王繼文
• Other Authors: Chen, Jeng-Chung
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/n6nd62

博士 === 國立清華大學 === 物理學系 === 106 === Low-frequency (1/f) electrical noise in transition metal dichalcogenides (TMDCs) field-effect transistor (FETs) is investigated in this thesis. The 1/f noise exists in almost all electronic devices and it sets a limit on how small the signal can be detected and processed. Semiconducting monolayer TMDCs are emergent materials for nano-devices and optoelectronic applications. TMDCs films are highly sensitivity to surface and interface conditions due to huge surface-to-volume ratio and the 1/f noise is related to surface condition. Investigating the origin of the 1/f noise in TMDC-based devices in order to reduce its strength is an interesting topic. In this thesis, the noise behavior of monolayer MoS2 and WS2 FETs are experimentally studied. In MoS2 FETs, high mobility and ohmic contact are achieved. With the help of polymer electrolyte (PE), MoS2 FETs can be effectively tuned to high carrier density region. The noise behavior of MoS2 FETs with PE-encapsulation is described by carrier number fluctuation model. By comparing the MoS2 FET with and without PE-encapsulation, we suggest that 1/f noise result from the interfacial traps between MoS2 and PE. On the other hand in WS2 FETs, Schottcky barriers are formed in the interface between WS2 and metal contacts. The low frequency noises show the 1/f spectrum but the dependence on current deviates from S_I∝I^2 relation. The carrier density dependence shows that the noise can be described by Hooge mobility fluctuation model.