Leaky Mode Resonance-Induced Sensitive Ultraviolet Photodetector Composed of Graphene/Small Diameter Silicon Nanowire Array Heterojunctions

Abstract

Ultraviolet photodetectors (UVPDs) based on wide band gap semiconductors (WBSs) are important for various civil and military applications. However, the relatively harsh preparation conditions and the high cost are unfavorable for commercialization. In this work, we proposed a non-WBS UVPD by using a silicon nanowire (SiNW) array with a diameter of 45 nm as building blocks. Device analysis revealed that the small diameter SiNW array covered with monolayer graphene was sensitive to UV light but insensitive to both visible and infrared light illumination, with a typical rejection ratio of 25. Specifically, the responsivity, specific detectivity, and external quantum efficiency under 365 nm illumination were estimated to be 0.151 A/W, 1.37 × 1012 Jones, and 62%, respectively, which are comparable to or even better than other WBS UVPDs. Such an abnormal photoelectrical characteristic is related to the HE1m leaky mode resonance (LMR), which is able to shift the peak absorption spectrum from near-infrared to UV regions. It is also revealed that this LMR is highly dependent on the diameter and the period of the SiNW array. These results show narrow band gap semiconductor nanostructures as promising building blocks for the assembly of sensitive UV photodetectors, which are very important for various optoelectronic devices and systems.

Near-Infrared Polarimetric Image Sensors Based on Ordered Sulfur-Passivation GaSb Nanowire Arrays

“…However, the NW devices of S-GaSb NWs with S 6.6% have the lowest dark currents implying that they would possess the higher responsivity ( R λ ) and detectivity ( D* ) values. The R λ and D* are key parameters for the photodetector, which could be calculated by the following equation ,− where P is the power intensity of incident light, S is the effective illumination area, B is the bandwidth, and e is the elementary electronic charge. The statistical results of R λ and D* are presented in Figure h,i.…”

“…In particular, III–V semiconductor nanowires (NWs) that are appropriate for contemporary silicon technology also have polarized photoresponse properties resulting from their anisotropic 1D geometry structure. , They display an anisotropic photoresponse for linear polarization light as long as the energy of the incident light is larger than that of the NW bandgap. ,, However, there are few reports about near-infrared polarization photodetectors based on narrow-bandgap III–V NWs. Furthermore, because of their distinguishing 1D structure features, narrow-bandgap III–V NWs can be assembled to ordered NWs arrays which could be constructed as flexible near-infrared polarimetric image sensors. ,, They possess the advantages of light weight, portability, and low cost compared with the commercial polarization detection systems consisting of lens and circuit systems. − More in-depth research is needed and expected.…”

“…Furthermore, because of their distinguishing 1D structure features, narrow-bandgap III−V NWs can be assembled to ordered NWs arrays which could be constructed as flexible near-infrared polarimetric image sensors. 14,16,17 polarization detection systems consisting of lens and circuit systems. 17−19 More in-depth research is needed and expected.…”

Remarkable Noise Reduction in High-Stability Self-Powered Doped Graphene/Si-Quantum Dot Broadband Photodetectors by Using Graphene Quantum Dots as an Interlayer

“…In contrast, the EQE looks very flat from λ = ∼970 nm down to ∼400 nm because the decrease of R at the lower λ is compensated by the decrease of λ itself, as clearly seen in the EQE formula: EQE = ( hc / q ) (1/λ)­R, where h is the Planck constant and q is the electron charge. Especially, the EQE reaches ∼90% in the visible range (∼400 to ∼900 nm), much larger than those previously known for GR/Si-junction-based PDs, ,,,,,,− as summarized in Table . In contrast, the R /EQE of the PD counterpart with pristine (undoped)-GR TCE showed a relatively low 0.34 A W –1 /71% at λ = 600 nm (Figure S5), respectively, because of the high sheet resistance (640 Ω/sq) of the pristine GR despite the perfect transmittance.…”

“…Nevertheless, the photoresponse is limited in its further enhancement owing to the large leakage current caused by relatively high-density defect states at the GR/Si interface . To overcome this problem, many researchers have made a lot of efforts to improve the performance by giving varieties to the basic structure of the GR/Si heterojunction. − Si quantum dots (SiQDs)-embedded SiO 2 (SiQDs:SiO 2 ) has been highly attractive for photonic device applications, thanks to distinctive properties such as stronger light absorption and faster photo-sensing than bulk Si. Particularly, SiQDs:SiO 2 was well applied in solar cells and PDs. − The optoelectronic properties of the GR/Si heterojunction proved to be improved by employing SiQDs:SiO 2 between GR and a Si wafer in previous studies, ,− resulting from the improvement of the band profiles at the GR/Si interface.…”