We report on the simple fabrication of monolayer graphene (MLG)/germanium (Ge) heterojunction for infrared (IR) light sensing. It is found that the as-fabricated Schottky junction detector exhibits obvious photovoltaic characteristics, and is sensitive to IR light with high Ilight/Idark ratio of 2 × 10(4) at zero bias voltage. The responsivity and detectivity are as high as 51.8 mA W(-1) and 1.38 × 10(10) cm Hz(1/2) W(-1), respectively. Further photoresponse study reveals that the photovoltaic IR detector displays excellent spectral selectivity with peak sensitivity at 1400 nm, and a fast light response speed of microsecond rise/fall time with good reproducibility and long-term stability. The generality of the above results suggests that the present MLG/Ge IR photodetector would have great potential for future optoelectronic device applications.
A new Schottky junction ultraviolet photodetector (UVPD) is fabricated by coating a free-standing ZnO nanorod (ZnONR) array with a layer of transparent monolayer graphene (MLG) film. The single-crystalline [0001]-oriented ZnONR array has a length of about 8-11 μm, and a diameter of 100∼600 nm. Finite element method (FEM) simulation results show that this novel nanostructure array/MLG heterojunction can trap UV photons effectively within the ZnONRs. By studying the I-V characteristics in the temperature range of 80-300 K, the barrier heights of the MLG film/ZnONR array Schottky barrier are estimated at different temperatures. Interestingly, the heterojunction diode with typical rectifying characteristics exhibits a high sensitivity to UV light illumination and a quick response of millisecond rise time/fall times with excellent reproducibility, whereas it is weakly sensitive to visible light irradiation. It is also observed that this UV photodetector (PD) is capable of monitoring a fast switching light with a frequency as high as 2250 Hz. The generality of the above results suggest that this MLG film/ZnONR array Schottky junction UVPD will have potential application in future optoelectronic devices.
Silicon nanostructure-based solar cells have lately intrigued intensive interest because of their promising potential in next-generation solar energy conversion devices. Herein, we report a silicon nanowire (SiNW) array/carbon quantum dot (CQD) core-shell heterojunction photovoltaic device by directly coating Ag-assisted chemical-etched SiNW arrays with CQDs. The heterojunction with a barrier height of 0.75 eV exhibited excellent rectifying behavior with a rectification ratio of 10(3) at ±0.8 V in the dark and power conversion efficiency (PCE) as high as 9.10% under AM 1.5G irradiation. It is believed that such a high PCE comes from the improved optical absorption as well as the optimized carrier transfer and collection capability. Furthermore, the heterojunction could function as a high-performance self-driven visible light photodetector operating in a wide switching wavelength with good stability, high sensitivity, and fast response speed. It is expected that the present SiNW array/CQD core-shell heterojunction device could find potential applications in future high-performance optoelectronic devices.
A MoSe2/Si heterojunction photodetector is constructed by depositing MoSe2 film with vertically standing layered structure on Si substrate. Graphene transparent electrode is utilized to further enhance the separation and transport of photogenerated carriers. The device shows excellent performance in terms of wide response spectrum of UV–visible–NIR, high detectivity of 7.13 × 1010 Jones, and ultrafast response speed of ≈270 ns, unveiling the great potential for the heterojunction for high‐performance optoelectronic devices.
Ultrathin Bi2 S3 nanosheets with thicknesses down to 2.2 nm are fabricated. The resultant ultrathin Bi2 S3 -based photoconductor shows high sensitivity to visible-near infrared light from 405 to 780 nm with a high external photoresponsivity up to 4.4 A W(-1) , high detectivity of ≈10(11) Jones, relatively fast response time of ≈10 μs, and high flexibility and durability.
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