Enhanced optoelectronic performance from the Ti-doped ZnO nanowires

Chang, Li‐Wei; Sung, Yung-Chiao; Yeh, J. Andrew; Shih, Han C.

doi:10.1063/1.3554686

Cited by 28 publications

(22 citation statements)

References 40 publications

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“…The UV blueshift was also detected in the cathodoluminescence (CL) spectra of ZnO NWs irradiated with 30-keV Ti + ions. Nevertheless, in this case, the visible emission did not suffered changes with the implantation doses [29], contrary to the behavior observed by Wang et al [30] who reported a complete disappearance of the visible emission from ZnO NWs irradiated with 2-keV H + ions. Hence, the modification of the luminescence properties of ZnO after irradiation experiments is still not clearly understood and, even less, after low energy irradiation experiments.…”

Section: Introductioncontrasting

confidence: 71%

Modification of the optical and structural properties of ZnO nanowires by low-energy Ar+ ion sputtering

et al. 2013

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The effects of low-energy (≤2 kV) Ar+ irradiation on the optical and structural properties of zinc oxide (ZnO) nanowires (NWs) grown by a simple and cost-effective low-temperature technique were investigated. Both photoluminescence spectra from ZnO NW-coated films and cathodoluminescence analysis of individual ZnO NWs demonstrated obvious evidences of ultraviolet/visible luminescent enhancement with respect to irradiation fluence. Annihilation of the thinner ZnO NWs after the ion bombardment was appreciated by means of high-resolution scanning electron microscopy and transmission electron microscopy (TEM), which results in an increasing NW mean diameter for increasing irradiation fluences. Corresponding structural analysis by TEM pointed out not only significant changes in the morphology but also in the microstructure of these NWs, revealing certain radiation-sensitive behavior. The possible mechanisms accounting for the decrease of the deep-level emissions in the NWs with the increasing irradiation fluences are discussed according to their structural modifications.

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Section: Introductioncontrasting

confidence: 71%

Modification of the optical and structural properties of ZnO nanowires by low-energy Ar+ ion sputtering

et al. 2013

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“…Thus, the optimum behaviour of Ti as an electrical dopant takes place for 10 concentrations below 1 at.%. A similar behaviour, but with a Ti load threshold of 1.3 at.%, has been reported for 500nm 16 43 . According to the above exposed, ZnO samples doped with a 0.5at.% of Ti and thicknesses down to 10nm may be suitable for electronic and optoelectronic devices, 25 solar cells, photoelectrodes, photocatalysts or sensors.…”

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confidence: 50%

Coordination chemistry of titanium and zinc in Ti(1−x)Zn2xO2 (0 ≤x≤ 1) ultrathin films grown by DC reactive magnetron sputtering

et al. 2012

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X-ray Absorption Near Edge Structure (XANES) and Rutherford Backscattering Spectroscopy (RBS) were used to explore the structural phase and composition transitions of ultrathin films with Ti (1-x) Zn 2x O 2 stoichiometries, from very 10 low (~0.5 at.%) to high (~25at.%) titanium content. In this way, the coordination chemistry of Ti 4+ and Zn 2+ cations was examined for a wide range of oxide compositions.Transition metal doping and formation of mixed oxides are 15 widely used mechanisms to improve the intrinsic properties of binary oxides. Both procedures have been decisive to explain the spectacular increase of applications based on ZnO and TiO 2 films. Proven applications of metal-doped ZnO in optoelectronic 20 devices include photovoltaic and dye sensitized solar cells, flat panel displays, photodetectors, gas sensors, light emitting diodes and blue laser diodes [1][2][3][4] . The vast majority of previous work on doped ZnO films is related to doping with group III elements. In particular Al, Ga and In trivalent cations have been extensively 25 used to enhance the n-type conductivity of ZnO films [5][6][7][8][9][10][11] . Fewer studies have been performed on quadrivalent dopants as titanium, which have one more valence than the trivalent cations and can provide two free electrons per atom to improve the conductivity of the ZnO host. In particular the Ti 4+ cation has a slightly smaller 30 radius (6.8 nm) than Zn 2+ (7.4 nm) and, thus, it can act as a suitable donor in ZnO films. Some authors have reported an enhancement of the conductivity in Ti-ZnO (TZO) films for low titanium content (<1.5 at%) [12][13][14][15][16] . However, the conduction mechanism of the metal-semiconductor transition in ZnO is still unclear [17][18] . In turn, ZnO-TiO 2 mixed oxides have been widely studied to be used as gas sensors [19][20] inverse spinel crystal structure with a unit cell a = 0.846 nm), zinc meta-titanate ZnTiO 3 (either cubic inverse defect spinel, a = 0.840 nm or hexagonal ilmenite structure, a = 0.507 nm) and Zn 2 Ti 3 O 8 (cubic inverse defect spinel, a = 0.843 nm) are still under debate 27-29 . 50 Despite the extensive studies performed on the individual TZO and ZnO-TiO2 systems in areas such as photovoltaics, photocatalysis or optoelectronics, there is a lack of a systematic work to fully understand how the Ti incorporation takes place in the ZnO oxide structure either as dopant or to form mixed oxides. 55In particular, one of the current technological challenges is the elucidation of such mechanism for nanostructured and ultrathin films due to the size-dependent electronic and optical properties of these semiconductor materials, as discussed in ref. O (α, α) 16 O at that particular energy and, therefore, to improve the sensitivity to oxygen. The chemical composition values have been extracted using the RBX software 34 . The X-ray Absorption Near Edge Structure (XANES) measurements were done at the PM4 beamline of the Bessy II 95 synchrotron facility (Berlin, Germany), using the SurICat endstation. Th...

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“…Next, the surface roughness (due to the presence of surface defects) and impurity may cause electron scattering, leading to the limited mobility. It is still higher than other application of photodetector of oxide semiconductor materials [33-35]. This implies that it may affect the sensitivity of the photodetector.…”

Section: Resultsmentioning

confidence: 95%

High sensitivity of middle-wavelength infrared photodetectors based on an individual InSb nanowire

Kuo

Lin

et al. 2013

Nanoscale Res Lett

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Single-crystal indium antimony (InSb) nanowire was fabricated into middle-infrared photodetectors based on a metal–semiconductor-metal (M-S-M) structure. The InSb nanowires were synthesized using an electrochemical method at room temperature. The characteristics of the FET reveal an electron concentration of 3.6 × 1017 cm−3 and an electron mobility of 215.25 cm2 V−1 s−1. The photodetectors exhibit good photoconductive performance, excellent stability, reproducibility, superior responsivity (8.4 × 104 A W−1), and quantum efficiency (1.96 × 106%). These superior properties are attributed to the high surface-to-volume ratio and single-crystal 1D nanostructure of photodetectors that significantly reduce the scattering, trapping, and the transit time between the electrodes during the transport process. Furthermore, the M-S-M structure can effectively enhance space charge effect by the formation of the Schottky contacts, which significantly assists with the electron injection and photocurrent gain.

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Enhanced optoelectronic performance from the Ti-doped ZnO nanowires

Cited by 28 publications

References 40 publications

Modification of the optical and structural properties of ZnO nanowires by low-energy Ar+ ion sputtering

Modification of the optical and structural properties of ZnO nanowires by low-energy Ar+ ion sputtering

Coordination chemistry of titanium and zinc in Ti(1−x)Zn2xO2 (0 ≤x≤ 1) ultrathin films grown by DC reactive magnetron sputtering

High sensitivity of middle-wavelength infrared photodetectors based on an individual InSb nanowire

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