Limits...
Photoresponsive and gas sensing field-effect transistors based on multilayer WS₂ nanoflakes.

Huo N, Yang S, Wei Z, Li SS, Xia JB, Li J - Sci Rep (2014)

Bottom Line: The photoelectrical properties of multilayer WS₂ nanoflakes including field-effect, photosensitive and gas sensing are comprehensively and systematically studied.The ethanol and NH₃ molecules can serve as electron donors to enhance the Rλ and EQE significantly.Under the NH3 atmosphere, the maximum Rλ and EQE can even reach 884 A/W and 1.7 × 10(5)%, respectively.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of SciencesP.O. Box 912, Beijing 100083, China.

ABSTRACT
The photoelectrical properties of multilayer WS₂ nanoflakes including field-effect, photosensitive and gas sensing are comprehensively and systematically studied. The transistors perform an n-type behavior with electron mobility of 12 cm(2)/Vs and exhibit high photosensitive characteristics with response time (τ) of <20 ms, photo-responsivity (Rλ) of 5.7 A/W and external quantum efficiency (EQE) of 1118%. In addition, charge transfer can appear between the multilayer WS₂ nanoflakes and the physical-adsorbed gas molecules, greatly influencing the photoelectrical properties of our devices. The ethanol and NH₃ molecules can serve as electron donors to enhance the Rλ and EQE significantly. Under the NH3 atmosphere, the maximum Rλ and EQE can even reach 884 A/W and 1.7 × 10(5)%, respectively. This work demonstrates that multilayer WS₂ nanoflakes possess important potential for applications in field-effect transistors, highly sensitive photodetectors, and gas sensors, and it will open new way to develop two-dimensional (2D) WS₂-based optoelectronics.

No MeSH data available.


Related in: MedlinePlus

Characterization of the multilayer WS2 nanoflakes.(a) Primitive cell and three-dimensional schematic representation of a typical WS2 structure with the sulfur atoms in yellow and the tungsten atoms in purple. Atomic force microscopy (AFM) image (b) and scanning electron microscopy (SEM) image (c) of the actual transistor based on multilayer WS2 nanoflakes. (d) Schematic diagram of the device. The thickness of WS2 nanoflakes is 42 nm. The width (W) and length (L) of the channel in the device is 15 μm and 20 μm, respectively. (e) Room-temperature Raman spectrum from the multilayer WS2 nanoflakes, using the 532 nm laser.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4048886&req=5

f1: Characterization of the multilayer WS2 nanoflakes.(a) Primitive cell and three-dimensional schematic representation of a typical WS2 structure with the sulfur atoms in yellow and the tungsten atoms in purple. Atomic force microscopy (AFM) image (b) and scanning electron microscopy (SEM) image (c) of the actual transistor based on multilayer WS2 nanoflakes. (d) Schematic diagram of the device. The thickness of WS2 nanoflakes is 42 nm. The width (W) and length (L) of the channel in the device is 15 μm and 20 μm, respectively. (e) Room-temperature Raman spectrum from the multilayer WS2 nanoflakes, using the 532 nm laser.

Mentions: Bulk WS2 is an indirect-bandgap (1.4 eV) semiconductor, but can turn into a direct-bandgap (2.1 eV) material when exfoliated into the monolayer state34. Each single plane of WS2 comprises a trilayer composed of a tungsten layer sandwiched between two sulfur layers in a trigonal prismatic coordination as shown in Figure 1a. The multilayer WS2 nanoflakes based transistors were fabricated with a coplanar electrode geometry by “gold-wire mask moving” technique3536. Through the AFM (Figure 1b and Figure S1) and SEM (Figure 1c) images of actual devices with SiO2 as bottom gating, the thickness of the WS2 nanoflakes is about 42 nm, and the width and length of the channel are 20 μm and 15 μm, respectively. Figure 1d shows the schematic diagram of the device. EDX (Figure S2) results indicate the existence of S and W elements with an atom ratio of 2 in the WS2 nanoflakes.


Photoresponsive and gas sensing field-effect transistors based on multilayer WS₂ nanoflakes.

Huo N, Yang S, Wei Z, Li SS, Xia JB, Li J - Sci Rep (2014)

Characterization of the multilayer WS2 nanoflakes.(a) Primitive cell and three-dimensional schematic representation of a typical WS2 structure with the sulfur atoms in yellow and the tungsten atoms in purple. Atomic force microscopy (AFM) image (b) and scanning electron microscopy (SEM) image (c) of the actual transistor based on multilayer WS2 nanoflakes. (d) Schematic diagram of the device. The thickness of WS2 nanoflakes is 42 nm. The width (W) and length (L) of the channel in the device is 15 μm and 20 μm, respectively. (e) Room-temperature Raman spectrum from the multilayer WS2 nanoflakes, using the 532 nm laser.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4048886&req=5

f1: Characterization of the multilayer WS2 nanoflakes.(a) Primitive cell and three-dimensional schematic representation of a typical WS2 structure with the sulfur atoms in yellow and the tungsten atoms in purple. Atomic force microscopy (AFM) image (b) and scanning electron microscopy (SEM) image (c) of the actual transistor based on multilayer WS2 nanoflakes. (d) Schematic diagram of the device. The thickness of WS2 nanoflakes is 42 nm. The width (W) and length (L) of the channel in the device is 15 μm and 20 μm, respectively. (e) Room-temperature Raman spectrum from the multilayer WS2 nanoflakes, using the 532 nm laser.
Mentions: Bulk WS2 is an indirect-bandgap (1.4 eV) semiconductor, but can turn into a direct-bandgap (2.1 eV) material when exfoliated into the monolayer state34. Each single plane of WS2 comprises a trilayer composed of a tungsten layer sandwiched between two sulfur layers in a trigonal prismatic coordination as shown in Figure 1a. The multilayer WS2 nanoflakes based transistors were fabricated with a coplanar electrode geometry by “gold-wire mask moving” technique3536. Through the AFM (Figure 1b and Figure S1) and SEM (Figure 1c) images of actual devices with SiO2 as bottom gating, the thickness of the WS2 nanoflakes is about 42 nm, and the width and length of the channel are 20 μm and 15 μm, respectively. Figure 1d shows the schematic diagram of the device. EDX (Figure S2) results indicate the existence of S and W elements with an atom ratio of 2 in the WS2 nanoflakes.

Bottom Line: The photoelectrical properties of multilayer WS₂ nanoflakes including field-effect, photosensitive and gas sensing are comprehensively and systematically studied.The ethanol and NH₃ molecules can serve as electron donors to enhance the Rλ and EQE significantly.Under the NH3 atmosphere, the maximum Rλ and EQE can even reach 884 A/W and 1.7 × 10(5)%, respectively.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of SciencesP.O. Box 912, Beijing 100083, China.

ABSTRACT
The photoelectrical properties of multilayer WS₂ nanoflakes including field-effect, photosensitive and gas sensing are comprehensively and systematically studied. The transistors perform an n-type behavior with electron mobility of 12 cm(2)/Vs and exhibit high photosensitive characteristics with response time (τ) of <20 ms, photo-responsivity (Rλ) of 5.7 A/W and external quantum efficiency (EQE) of 1118%. In addition, charge transfer can appear between the multilayer WS₂ nanoflakes and the physical-adsorbed gas molecules, greatly influencing the photoelectrical properties of our devices. The ethanol and NH₃ molecules can serve as electron donors to enhance the Rλ and EQE significantly. Under the NH3 atmosphere, the maximum Rλ and EQE can even reach 884 A/W and 1.7 × 10(5)%, respectively. This work demonstrates that multilayer WS₂ nanoflakes possess important potential for applications in field-effect transistors, highly sensitive photodetectors, and gas sensors, and it will open new way to develop two-dimensional (2D) WS₂-based optoelectronics.

No MeSH data available.


Related in: MedlinePlus