Correlation between grain size and optical properties in zinc oxide thin films

Matsumoto, Takahiro; Kato, Hiroyuki; Miyamoto, Kazuhiro; Sano, Megumi; Zhukov, Evgeniy Andreevich; Yao, Takafumi

doi:10.1063/1.1499991

Cited by 161 publications

(88 citation statements)

References 11 publications

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“…The decay time remains constant, pointing to a uniform distribution of dopant in the particles of various sizes. Matsumoto et al [10] reported the influence of particle size on the photoluminescence of undoped ZnO. In addition, they not only observed an increase in luminescence intensity but also an increase in the decay times.…”

Section: Alternate Low Temperature Synthesismentioning

confidence: 91%

Development of ZnO:Ga as an ultra-fast scintillator

Bourret-Courchesne¹,

Derenzo²,

Weber³

2009

Nuclear Instruments and Methods in Physics Research Section A:

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Abstract-We report on several methods for synthesizing the ultra-fast scintillator ZnO(Ga), and measurements of the resulting products. This material has characteristics that make it an excellent alpha detector for tagging the time and direction of individual neutrons produced by t-d and d-d neutron generators (associated particle imaging). The intensity and decay time are strongly dependent on the method used for dopant incorporation. We compare samples made by diffusion of Ga metal to samples made by solid state reaction between ZnO and Ga 2 O 3 followed by reduction in hydrogen. The latter is much more successful and has a pure, strong near-band-edge fluorescence and an ultra-fast decay time of the x-ray-excited luminescence. The luminescence increases dramatically as the temperature is reduced to 10K. We also present results of an alternate low-temperature synthesis that produces luminescent particles with a more uniform size distribution. We examine possible mechanisms for the bright near-band-edge scintillation and favor the explanation that it is due to the recombination of Ga 3+ donor electrons with ionization holes trapped on H + ion acceptors.

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Section: Alternate Low Temperature Synthesismentioning

confidence: 91%

Development of ZnO:Ga as an ultra-fast scintillator

Bourret-Courchesne¹,

Derenzo²,

Weber³

2009

Nuclear Instruments and Methods in Physics Research Section A:

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“…larger, and hence smaller grains will have more nonradiative relaxation centers from the surface states. 33,34 The increased nonradiative relaxation results in the noticeable decrease in the UV excitonic emission intensity. Thus, the optical quality of the samples increases with the increase in grain size.…”

Section: -3mentioning

confidence: 99%

Growth of CuCl thin films by magnetron sputtering for ultraviolet optoelectronic applications

Natarajan

Daniels

Cameron

et al. 2006

Journal of Applied Physics

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Copper ͑I͒ chloride ͑CuCl͒ is a potential candidate for ultraviolet ͑UV͒ optoelectronics due to its close lattice match with Si ͑mismatch less than 0.4%͒ and a high UV excitonic emission at room temperature. CuCl thin films were deposited using radio frequency magnetron sputtering technique. The influence of target to substrate distance ͑d ts ͒ and sputtering pressure on the composition, microstructure, and UV emission properties of the films were analyzed. The films deposited with shorter target to substrate spacing ͑d ts =3 cm͒ were found to be nonstoichiometric, and the film stoichiometry improves when the substrate is moved away from the target ͑d ts = 4.5 and 6 cm͒. A further increase in the spacing results in poor crystalline quality. The grain interface area increases when the sputtering pressure is increased from 1.1ϫ 10 −3 to 1 ϫ 10 −2 mbar at d ts = 6 cm. Room temperature cathodoluminescence spectrum shows an intense and sharp UV exciton ͑Z 3 ͒ emission at ϳ385 nm with a full width at half maximum of 16 nm for the films deposited at the optimum d ts of 6 cm and a pressure of 1.1ϫ 10 −3 mbar. A broad deep level emission in the green region ͑ ϳ515 nm͒ is also observed. The relative intensity of the UV to green emission peaks decreased when the sputtering pressure was increased, consistent with an increase in grain boundary area. The variation in the stoichiometry and the crystallinity are attributed to the change in the intensity and energy of the flux of materials from the target due to the interaction with the background gas molecules.

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“…9 A major asset of ZnO is that its Photoluminescence (PL) spectra consist of two emission components: a narrow UltraViolet (UV) peak at around 380 nm, which is correlated with the near band-edge (NBE) exciton emission, 10 and a broad visible (VIS) peak spanning from 450 to 750 nm, which is associated with deep level emission (DLE) from intrinsic and extrinsic defects. [11][12][13][14] The fabrication of high-quality ZnO films with strong UV or VIS emission is a challenging task; a high-temperature deposition or/and a post-deposition annealing scheme is usually required 15,16 with thermal annealing 17 and rapid thermal annealing, 18 which however are not compatible with temperature sensitive underlayers, such as thin metal layers. Consequently, laser annealing 19,20 (LA), being a cold process, is a favourable alternative for processing such structures.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence enhancement of ZnO via coupling with surface plasmons on Al thin films

Dellis

Kalfagiannis

Kassavetis

et al. 2017

Journal of Applied Physics

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We present that the ultra-violet emission of ZnO can be enhanced, as much as six-times its integral intensity, using an Al thin interlayer film between the Si substrate and ZnO thin film and a postfabrication laser annealing process. The laser annealing is a cold process that preserves the chemical state and integrity of the underlying aluminum layer, while it is essential for the improvement of the ZnO performance as a light emitter and leads to enhanced emission in the visible and in the ultraviolet spectral ranges. In all cases, the metal interlayer enhances the intensity of the emitted light, either through coupling of the surface plasmon that is excited at the Al/ZnO interface, in the case of light-emitting ZnO in the ultraviolet region, or by the increased back reflection from the Al layer, in the case of the visible emission. In order to evaluate the process and develop a solid understanding of the relevant physical phenomena, we investigated the effects of various metals as interlayers (Al, Ag, and Au), the metal interlayer thickness, and the incorporation of a dielectric spacer layer between Al and ZnO. Based on these experiments, Al emerged as the undisputable best choice of metal interlayers because of its compatibility with the laser annealing process, as well as due to its high optical reflectivity at 380 and 248 nm, which leads to the effective coupling with surface plasmons at the Al/ZnO interfaces at 380 nm and the secondary annealing of ZnO by the backreflected 248 nm laser beam. Published by AIP Publishing. [http://dx

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Correlation between grain size and optical properties in zinc oxide thin films

Cited by 161 publications

References 11 publications

Development of ZnO:Ga as an ultra-fast scintillator

Development of ZnO:Ga as an ultra-fast scintillator

Growth of CuCl thin films by magnetron sputtering for ultraviolet optoelectronic applications

Photoluminescence enhancement of ZnO via coupling with surface plasmons on Al thin films

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