THESIS
2017
xiii, 49 pages : color illustrations ; 30 cm
Abstract
The electronic and optoelectronic properties of MoS
2 and WS
2 devices and MoS
2/ WSe
2
heterojunctions have been studied in this thesis.
In transition metal dichalcogenides (TMDC) field effect transistors using ionic liquid as the
dielectric layer ambipolar transport behaviors are observed, which allows us directly extract the
energy gap of the thin films. In addition, the Schottky barrier height can be tuned by controlling
the doping level of TMDCs and almost eliminated when a positive gate voltage is applied.
Moreover, MoS
2/WSe
2 p-n junction fabricated by polymer-free dry transfer method shows
clearly a diode like rectification behavior and can be well tuned by back-gate voltage. Upon optical
illumination, both charge transfer process and recombination process occur at the juncti...[
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The electronic and optoelectronic properties of MoS
2 and WS
2 devices and MoS
2/ WSe
2
heterojunctions have been studied in this thesis.
In transition metal dichalcogenides (TMDC) field effect transistors using ionic liquid as the
dielectric layer ambipolar transport behaviors are observed, which allows us directly extract the
energy gap of the thin films. In addition, the Schottky barrier height can be tuned by controlling
the doping level of TMDCs and almost eliminated when a positive gate voltage is applied.
Moreover, MoS
2/WSe
2 p-n junction fabricated by polymer-free dry transfer method shows
clearly a diode like rectification behavior and can be well tuned by back-gate voltage. Upon optical
illumination, both charge transfer process and recombination process occur at the junction region.
By further comparing the photocurrent result and the photoluminescence (PL) under different
back-gate voltages, interlayer exciton recombination process and the interlayer charge transfer
process are found to compete against each other.
Our transport measurements show that both 2D devices or heterostructure have potential for
future application.
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