Abstract
Photoelectric functional material WS2 thin film on SiC substrate was synthesized. Both 15 and 150 nm thickness of WS2 film were deposited on an n-doped SiC substrate (7.37 × 1019 cm − 3) by pulsed laser deposition method. Optical properties of the WS2 / SiC material were discovered. (I) a photovoltaic effect: (1) there is a cutoff wavelength λc (661 nm), which means the wavelength of an incident monochromatic light must be less than λc in order to have the photovoltaic effect; (2) the incident light must be polarized. (3) It was found that the maximum open circuit voltage output is 6.3 V in a condition of 40 mW @ 532 nm. (II) Wavelength blueshift: when a laser of 532 nm is used in the experiment to incident perpendicularly through the thin layer WS2 / SiC film stack, which is driven by an external electric field, it is found that the 532-nm photons are blueshifted 1.33 nm under a 30 V (DC) voltage. We also find that the blueshift of the laser wavelength is tunable with the applied voltage. Inverse Compton scattering of the photon by both electron and hole is used to explain this blueshift, the consistency of experimental results and the theoretical calculation for the wavelength blueshift was found.
Highlights
(3) It was found that the maximum open circuit voltage output is 6.3 V in a condition of 40 mW @ 532 nm. (II) Wavelength blueshift: when a laser of 532 nm is used in the experiment to incident perpendicularly through the thin layer WS2∕SiC film stack, which is driven by an external electric field, it is found that the 532-nm photons are blueshifted 1.33 nm under a 30 V (DC) voltage
It is much easier to have a wafer size thin layer WS2 film, especially in optoelectronic device applications; it is necessary to investigate the optical natures of thin layered transition-metal dichalcogenides (TMDs) film
Atomic force microscopy data of the thin layer film, and STEM were used to characterize the material, which was revealed that the thin layer WS2 film on the n-doped SiC substrate is a fine WS2 film,[26] the details of the film formation and the correspondent characterization data can be found in SPIE-pulsed laser deposition (PLD)/TFPA 2019 (Qingdao, China, May 19 to 22, 2019)
Summary
Recent advances in two-dimensional (2-D) semiconductors, monolayer transition-metal dichalcogenides (TMDs), have attracted rapidly growing scientific interests for next-generation electrical and optoelectronic device applications.[1,2,3,4,5,6,7,8,9,10,11] A single layer of TMDs exhibits a totally new phenomenon, which can lead to 2-D nanoelectronic and nanophotonic applications owing to its unique physical, electrical, and optical properties.[12,13,14,15] Chemical vaporized deposition method was used to synthesize monolayer TMDs16–19 mainly; magnetron sputtering technique can be used to produce large thin layered TMDs films or even monolayer TMDs.[20]. The 15-nm-thick WS2∕SiC film and 150-nm-thick WS2∕SiC film were superimposed by WS2 − WS2 face to face together to form a film stack, and both n-doped SiC substrates on each side was used as electric electrode For this WS2∕SiC film stack, new optical properties about this material are discovered as follows: photovoltaic effect is related to a cutoff wavelength of the incident monochromatic light or laser, and the power of laser, as well as the polarization of the laser electric field. The maximum photovoltaic output voltage measurement was conducted by applying a commercial 532-nm laser (YRL-532-100) to a WS2∕SiC film stack. Voc varies linearly with the increase of laser power, and it reaches to a maximum of 6.3 V at 40 mW
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