Ultraporous Electron‐Depleted ZnO Nanoparticle Networks for Highly Sensitive Portable Visible‐Blind UV Photodetectors

Nasiri, Noushin; Bo, Renheng; Wang, Fan; Fu, Lan; Tricoli, Antonio

doi:10.1002/adma.201501517

Cited by 228 publications

(341 citation statements)

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“…Thus, decrease in diameter of ZnO NW could increase the relative width of the depletion layer and thus enhance the photo-to-dark current ratio. [6,23] The junction barrier height caused by the SBB effect could be estimated by [44] : [34] Pt/Ultraporous ZnO NP networks /Pt(300 mm) The role of metal/ semiconductor interface and photogeneration of free carriers in ZnO NW array PD are the same as that in single ZnO NW PD.…”

Section: Discussionmentioning

confidence: 99%

“…Figure 3a shows I-V curves of ZnO NW array-based device with and without light illumination. Photo-to-dark current ratio (I ph /I dark ) could be improved by decreasing the diameter of ZnO NWs, [33,34] and etching discontinuous patterns on the substrates for ZnO NW growth. The high dark current of the ZnO NW array-based device resulted from the formation of a ZnO layer on the roughened SiO 2 surface.…”

Section: Photoresponse Behavior Of Zno Nw Uv Pdsmentioning

confidence: 99%

“…We estimated the time constants of rise stage are t 1 ¼ 6.27 s and t 2 ¼ 37.1 s, and their relative weight factors are 85 and 15%, respectively, which give an average rise time constant of t r ¼ 11.02 s; the estimated time constants of the decay stage are t 1 ¼ 0.28 s and t 2 ¼ 6.85 s, with relative weight of 67 and 33%, respectively, producing an average decay time constant t d of 2.43 s. It was found that the rise process of NW array PD (1.38 s) is much faster than that of single NW PD (11.02 s), while the resetting process of ZnO NW array PD (4.05 s) is also comparable with that of single NW device (2.43 s). [6,9,11,14,16,19,20,22,25,27,[33][34][35][36][37][38][39][40][41][42] Compared to low temperature synthesized ZnO nanorods reported in reference, [35,36] ZnO NW arrays grown by CVD at high temperature have better crystal quality, which contributes to the high performance of our devices. Table 1 compares the photoresponse of different ZnO NW-based UV PDs as reported previously.…”

Section: Photoresponse Behavior Of Zno Nw Uv Pdsmentioning

confidence: 99%

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Direct Catalyst‐Free Chemical Vapor Deposition of ZnO Nanowire Array UV Photodetectors with Enhanced Photoresponse Speed

Zhan

et al. 2017

Adv Eng Mater

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ZnO-based photodetectors (PDs) have long response times at magnitude of tens to hundreds of seconds, hampering their practical UV detection. The slow oxygen chemisorption/desorption process is the main cause of the slow response of UV PDs based on single ZnO nanowires (NWs). Here, the authors find the response speed of ZnO NW-based UV PDs could be improved by directly fabricating UV PDs on entangled ZnO NW array grown on SiO 2 through a catalyst-free chemical vapor deposition (CVD) process. Specifically, the interconnections in ZnO NW array creates NW-NW junction barriers, which dominate the inter-wire charge transport. The switching of UV illumination induces fast tuning of NW-NW junction barrier height, which contributes to the enhanced response speed of the ZnO NW array UV PDs.

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Section: Discussionmentioning

confidence: 99%

Section: Photoresponse Behavior Of Zno Nw Uv Pdsmentioning

confidence: 99%

Section: Photoresponse Behavior Of Zno Nw Uv Pdsmentioning

confidence: 99%

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Direct Catalyst‐Free Chemical Vapor Deposition of ZnO Nanowire Array UV Photodetectors with Enhanced Photoresponse Speed

Zhan

et al. 2017

Adv Eng Mater

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“…The ZnO (E g = 3.37 eV) semiconductors, which possess a large exciton binding energy of 60 meV, are widely used for ultraviolet (UV) photoelectric devices [13][14][15][16][17][18][19]. However, the room temperature emission from ZnO nanostructures always display a broad deep level emission (DLE) in the visible region along with the weak near-band edge (NBE) emission in the UV region.…”

Section: Introductionmentioning

confidence: 99%

Investigation of localized and delocalized excitons in ZnO/ZnS core-shell heterostructured nanowires

Wei

Zhao

et al. 2016

Nanophotonics

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Abstract:The localized states in ZnO nanowires (NWs) through the growth of ZnS shell have been introduced in this paper. Morphology and optical properties of the ZnO/ ZnS core-shell heterostructured NWs after different rapid thermal annealing (RTA) treatments are investigated. Transmission electron microscopy measurements show the gradual disappearing of the jagged boundary between ZnO and ZnS with the increase of RTA temperature, while a decrease of interfacial composition fluctuation and a formation of ZnOS phase can be found after a RTA treatment of 300°C. Temperature-dependent photoluminescence exhibits the features of "S-shape" peak positions and a "valley shape" for the emission width, implying the existence of localized excitons in the core-shell NWs. Moreover, it is noted that the RTA treatments can lower the localized degree which is confirmed by optical measurement. The results indicate that the optical behavior of excitons in ZnO/ZnS core-shell heterostructured NWs can be manipulated by appropriate thermal treatments, which is very important for their practical device applications.

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“…[2] With recent advances in smart health care technology, the demand for transparent and flexible UV sensors that can be integrated into portable or wearable devices is rapidly growing for numerous potential applications, including smart watches/bands, smart glasses, and patchable devices. [6] To overcome these shortcomings, nanomaterial-based UV sensors have been extensively studied. [6] To overcome these shortcomings, nanomaterial-based UV sensors have been extensively studied.…”

mentioning

confidence: 99%

A Fully Transparent, Flexible, Sensitive, and Visible‐Blind Ultraviolet Sensor Based on Carbon Nanotube–Graphene Hybrid

Pyo

Choi

Kim

2018

Adv Elect Materials

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generates free-radical chemical species that cause various skin diseases such as inflammatory disorders, aging, and skin cancer. [2] With recent advances in smart health care technology, the demand for transparent and flexible UV sensors that can be integrated into portable or wearable devices is rapidly growing for numerous potential applications, including smart watches/bands, smart glasses, and patchable devices. [3][4][5] However, Si-based UV sensors, the most established commercial sensors, are unsuitable for use in such applications because of their lack of mechanical flexibility and optical transparency and their need for high operating voltage and a long-pass filter to block low energy photons. [6] To overcome these shortcomings, nanomaterial-based UV sensors have been extensively studied. [7][8][9][10] 1D and 2D semiconducting materials such as ZnO, TiO 2 , GaTe, and MoS 2 are promising candidates for photodetection because of their direct bandgap at room temperature, transparency in the visible region, and mechanical flexibility. [11][12][13][14] Accordingly, those materials have been used for the active component of sensitive, transparent, and flexible UV sensors. [15][16][17][18][19] The UV sensors based on nanomaterials generally show high-performance in terms of photoresponsivity and response/recovery time, but most of them still rely on intrinsically opaque metal electrodes. [15,16] Although a few works have reported UV sensors where all the active or passive components were transparent, [17,18] the brittle electrode (e.g., indium tin oxide; ITO) limits the flexibility of the sensor, since ITO easily fractures under a strain of only 1%. [20] To achieve both optical transparency and mechanical flexibility, all the components of the UV sensor must be transparent and flexible. In addition, contact resistance between the photoactive material and the electrodes is a significant factor influencing the performance of UV sensors and must be considered in order to induce an effective charge transfer from the photoactive material to the electrodes. [21,22] This implies that selection of both photoresponsive and electrode materials would regulate the overall photoresponse as well as transparency and flexibility of the UV sensor.One of the promising alternatives is a combination of carbon nanomaterials, including 1D carbon nanotubes (CNTs) and

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Ultraporous Electron‐Depleted ZnO Nanoparticle Networks for Highly Sensitive Portable Visible‐Blind UV Photodetectors

Cited by 228 publications

References 33 publications

Direct Catalyst‐Free Chemical Vapor Deposition of ZnO Nanowire Array UV Photodetectors with Enhanced Photoresponse Speed

Direct Catalyst‐Free Chemical Vapor Deposition of ZnO Nanowire Array UV Photodetectors with Enhanced Photoresponse Speed

Investigation of localized and delocalized excitons in ZnO/ZnS core-shell heterostructured nanowires

A Fully Transparent, Flexible, Sensitive, and Visible‐Blind Ultraviolet Sensor Based on Carbon Nanotube–Graphene Hybrid

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