High—Performance Solar‐Blind Deep Ultraviolet Photodetector Based on Individual Single‐Crystalline Zn<sub>2</sub>GeO<sub>4</sub> Nanowire

Zhou, Xing; Zhang, Qi; Gan, Lin; Li, Xin; Li, Huiqiao; Zhang, Yue; Golberg, Dmitri; Zhai, Tianyou

doi:10.1002/adfm.201504135

Cited by 174 publications

(117 citation statements)

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“…The current exhibits a linear increase as the voltage rises, indicating ohmic contacts between GeSe 2 and the electrodes. Mott had proposed a model for the conduction process of optical-phonon-assisted hopping of small polarons between localized states; it is represented by the following: [43,44] σ ν α To further investigate the electrical transport mechanism at different temperatures, we continued to look at trends as a function of inverse temperature and considered the temperature ranges as part of two different groups (Figure 5c,d).…”

Section: Resultsmentioning

confidence: 99%

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Zhou

et al. 2017

Adv Funct Materials

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103

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As a layered p-type semiconductor with a wide bandgap of 2.7 eV, GeSe 2 can compensate for the rarity of p-type semiconductors, which are desired for the production of high-integration logic circuits with low power consumption. Herein, ultrathin 2D single crystals of β-GeSe 2 are produced using van der Waals epitaxy and halide assistance; each crystalline flake is ≈7 nm thick and shaped as a rhombus. The optical and electrical properties of the flakes are studied systematically, and the temperature-dependent Raman spectra of the flakes reveal that the intensity of the Raman peaks decrease with increasing temperature. Low-temperature electrical measurements suggest that the variable-range hopping model is best for describing the electrical transport at 20-180 K; meanwhile, optical-phonon-assisted hopping can account for the transport behavior at 180-460 K. Impressively, the angle-resolved polarized Raman measurements indicate strong in-plane anisotropy of the rhombic GeSe 2 flake under a parallel polarization configuration, which may result from the low symmetry of the monoclinic crystal structure of GeSe 2 . Furthermore, a photodetector based on a rhombic GeSe 2 flake is constructed and shown to exhibit a high responsivity of 2.5 A W −1 and a fast response of ≈0.2 s. flakes under a parallel polarization configuration. Additionally, a flake is used to produce a photodetector, which exhibits a high responsivity of 2.5 A W −1 and a fast response of ≈0.2 s.

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Section: Resultsmentioning

confidence: 99%

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Zhou

et al. 2017

Adv Funct Materials

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103

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“…Such excellent performance in the broad spectral range (UV and visible) favorably distinguishes VO 2 /TiO 2 :Nb heterostructures from many other materials recently proposed for highly efficient UV detection such as AlGaN, β‐Ga 2 O 3 , GaN, TiO 2 , Zn 2 GeO 4 , ZnMgO, and ZnO . These materials tend to have properties that are a detriment for practical commercial implementations, as they tend have narrow detection bandwidths, require a voltage bias, and/or may require complicated fabrication methods hindering production scalability . On a contrary, the deposition of the VO 2 films via magnetron sputtering is a cost efficient, scalable production technique being suitable for practical device development and production.…”

mentioning

confidence: 99%

Growth and Characterization of Vanadium Dioxide/Niobium Doped Titanium Dioxide Heterostructures for Ultraviolet Detection

Creeden

Madaras

Beringer

et al. 2019

Advanced Optical Materials

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heterostructures from many other materials recently proposed for highly efficient UV detection such as AlGaN, [6][7][8][9] β-Ga 2 O 3 , [10,11] GaN, [7,12] TiO 2 , [13] Zn 2 GeO 4 , [14] ZnMgO, [15] and ZnO. [16,17] These materials tend to have properties that are a detriment for practical commercial implementations, as they tend have narrow detection bandwidths, [7][8][9][10]12,14] require a voltage bias, [7,8,10,[12][13][14][15][16][17] and/or may require complicated fabrication methods hindering production scalability. [6,10,11,16] On a contrary, the deposition of the VO 2 films via magnetron sputtering is a cost efficient, scalable production technique being suitable for practical device development and production. That fact, in addition to its highefficiency broadband UV detection with zero bias at convenient temperature range asserts the VO 2 /TiO 2 :Nb heterostructure as a novel, promising approach to addressing the need for efficient UV detection.To determine the photoconductive properties of our detectors, we used a four-point probe measurement system for photocurrent detection via four beryllium copper probes on the surface of the VO 2 film under 0 V bias. Typical photocurrent and dark current measurements are shown in Figure 1a), where we define the dark current as a residual low current measured in absence of any illumination; typically, it is associated with thermal fluctuations within the sample. [18] By subtracting the dark current from the photocurrent ΔI, we calculated the EQE and responsivity R λ of the heterojunction using the following equations [19][20][21][22][23] EQE hcR eλ = λ (1)Here P is the total detected light power, λ is the excitation wavelength, h is the Plank constant, e is the electron charge, and c is the speed of light in vacuum. Figure 1b shows the quantum efficiency measured for a 15 nm VO 2 film, measured for both, near UV (NUV) and UV-C light with varied optical powers. While we observed a gradual increase in EQE for lower powers, we consistently measured EQE above 100% in The properties of VO 2 /TiO 2 :Nb heterostructures are engineered for their potential use in ultraviolet (UV) detection and observed external quantum efficiency (EQE) exceeding 100% in both near UV (405 nm) and UV-C (254 nm) spectral regions. The proposed UV detection scheme is based on vanadium dioxide (VO 2 ) thin films epitaxially grown on niobium doped titanium dioxide (TiO 2 :Nb). Such VO 2 /TiO 2 :Nb heterostructure exhibits enhanced photocurrent due to cation doping engineering in a space-charge region thus yielding favorable conditions for hole tunneling from TiO 2 :Nb into VO 2 . The heterostructure is engineered and photocurrent is optimized by varying the VO 2 film thickness, reaching up to 5000% EQE for 405 nm and up to 17 000% EQE for 254 nm light, indicating that the VO 2 /TiO 2 :Nb system can be fine-tuned for efficient UV photodetection.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adom.201901143.Wide bandgap semiconductors f...

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“…A key issue related to the growth of nanowires is how to induce 1D crystal growth in a controlled manner. Regarding this, many approaches have been studied, including vapor–liquid–solid (VLS), chemical vapor deposition (CVD),[36b,63] wet synthesis, and pulsed laser deposition (PLD) …”

Section: Nanostructured Photodetector Architecturesmentioning

confidence: 99%

Nanoarchitechtonics of Visible‐Blind Ultraviolet Photodetector Materials: Critical Features and Nano‐Microfabrication

Nasiri

Jin

Tricoli

2018

Advanced Optical Materials

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Low-dimensional materials are usually classified into 0D, [19b,20] 1D, [2b,21] and 2D. [22] Quantum dots (QDs), [23] nanotubes, [24] nanowires, [25] nanorods, [18,26] nanobelts, [22a,27] core/ shell structures, [28] nanostructure arrays, [19a,29] epitaxial film, and heterostructures [30] are regarded as the future building blocks of visible-blind UV photodetectors. Compared to traditional thinfilm and bulk materials, low-dimensional nanostructured UV photodetectors are usually characterized by higher responsivity and photoconductivity gain, [1c,31] due to their high surface-areato-volume ratios and the nanoscale confined carrier transport kinetics. [3c,9,25b,32] The large surface-to-volume ratio significantly increases the number of surface trap states that can prolong the photocarrier lifetime by delaying the electron-hole recombination process. [1b,3c,9] In fact, the photoexcited carriers can be trapped by surface trap states and in that case their decay dynamics is dominated by the escape time from the traps. [33] The reduced dimensionality can confine the charge carrier transport path shortening the transit time and reducing recombination events. [3c] Nanostructured wide bandgap UV photodetectors have been produced by several methods, such as magnetron sputtering, [34] pulsed laser deposition, [35] chemical vapor deposition, [36] flame spray pyrolysis, [2d,9,15] and sol-gel. [37] A critical aspect remains how to accurately control the composition and hierarchical arrangement from the atomic scale of surface and bulk defects to the microscale of the active device area. The latter has been shown to be a dominant feature resulting in significant variation in the UV light response of quasi-identical nanomaterials. [9,25b,38] For instance, ZnO nanowires are usually reported to achieve orders of magnitude higher responsivity and detectivity than nanothin ZnO films. Similarly, ultraporous nanoparticle networks have shown thousand folds higher photo to dark-current ratios than more densely arranged ZnO nanoparticle layers resulting in among the highest detectivity reported for such 0D materials. [3c,9,39] Here, we present a comprehensive review of the latest achievements and research directions on the multiscale engineering of wide bandgap semiconductor materials for photodetection of UV light. We will focus on the impact of the nano-to microscale material hierarchy discussing commonalities and discrepancies across materials and morphologies. We will conclude with a review of the rapidly emerging trends and promising strategies for overcoming remaining issues for the engineering of the next generation of miniaturized wide bandgap semiconductors UV photodetectors for wearable and easily deployable devices. Photodetection MechanismWide bandgap semiconductors have been investigated in many recent studies to understand the fundamental process and enhancing the response to the UV light. [9,15,25b,40] The photoresponse characteristics of nanostructured devices are significantly influenced by a number of...

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High—Performance Solar‐Blind Deep Ultraviolet Photodetector Based on Individual Single‐Crystalline Zn₂GeO₄ Nanowire

Cited by 174 publications

References 74 publications

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Growth and Characterization of Vanadium Dioxide/Niobium Doped Titanium Dioxide Heterostructures for Ultraviolet Detection

Nanoarchitechtonics of Visible‐Blind Ultraviolet Photodetector Materials: Critical Features and Nano‐Microfabrication

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High—Performance Solar‐Blind Deep Ultraviolet Photodetector Based on Individual Single‐Crystalline Zn2GeO4 Nanowire

Cited by 174 publications

References 74 publications

Ultrathin 2D GeSe2 Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Ultrathin 2D GeSe2 Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Growth and Characterization of Vanadium Dioxide/Niobium Doped Titanium Dioxide Heterostructures for Ultraviolet Detection

Nanoarchitechtonics of Visible‐Blind Ultraviolet Photodetector Materials: Critical Features and Nano‐Microfabrication

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High—Performance Solar‐Blind Deep Ultraviolet Photodetector Based on Individual Single‐Crystalline Zn₂GeO₄ Nanowire

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy

Ultrathin 2D GeSe₂ Rhombic Flakes with High Anisotropy Realized by Van der Waals Epitaxy