Browsing by Author "Chang, Xiang-Rui"

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Enhancement of field-effect mobility in molybdenum-disulfide transistor through the treatment of low-power oxygen plasma
(2016-09)
Chen, Kuan-Chao
;
Wu, Chong-Rong
;
Chang, Xiang-Rui
;
Chang, Shu-Wei
;
Lee, Si-Chen
We experimentally demonstrate that the treatment with low-power oxygen plasma can raise the field-effect mobility in molybdenum-sulfide (MoS2) transistors from 0.01 to 9.6 cm(2)V(-1)s(-1), which is an increment of about three orders of magnitude. The decrease in threshold voltage and the increase in the drain current of the devices indicate that the electron density increases significantly after the mild plasma treatment. The emergence of Mo-O characteristics but the suppression of Mo-S features on the X-ray photoelectron spectrum of the plasma-treated sample suggests that a portion of the MoS2 film becomes conductive molybdenum oxide. This transformation may considerably upgrade the performance of MoS2 transistors. (C) 2016 The Japan Society of Applied Physics
Multilayer MoS2 prepared by one-time and repeated chemical vapor depositions: anomalous Raman shifts and transistors with high ON/OFF ratio
(2015-11-04)
Wu, Chong-Rong
;
Chang, Xiang-Rui
;
Chang, Shu-Wei
;
Chang, Chung-En
;
Wu, Chao-Hsin
We show that multilayer molybdenum disulfide (MoS2) grown with the chemical vapor deposition (CVD) may exhibit quite distinct behaviors of Raman shifts from those of exfoliated ones. The anomalous Raman shifts depend on CVD growth modes and are attributed to the modified dielectric screening and interlayer coupling of MoS2 in various growth conditions. With repeated CVD growths, we demonstrated the precise control over the layer number of MoS2. A decently large drain current, high ON/OFF ratio of 10(5), and enhanced field-effect mobility can be achieved in transistors fabricated on the six-layer MoS2.