<i>In Situ</i> X-ray Absorption Near-Edge Structure Spectroscopy of ZnO Nanowire Growth During Chemical Bath Deposition

McPeak, Kevin M.; Becker, Matthew A.; Britton, Nathan G.; Majidi, Hasti; Bunker, Bruce A.; Baxter, Jason B.

doi:10.1021/cm102155m

Cited by 64 publications

(72 citation statements)

References 50 publications

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“…Since HMTA does not bind with Zn 2+ ion in the bath, 13 HMTA may be involved in the transition state of the Zn-TAA reaction or directly with the decomposition of TAA. A comprehensive study on the possible reaction pathways of TAA was discussed by Bayoń et al 35 for deposition of In(OH) x S y .…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…We have previously shown that HMTA does not complex with Zn, and addition of HMTA should not reduce the free Zn 2+ ion concentration. 13 Instead, addition of HMTA should significantly increase the deposition rate by maintaining moderate pH to provide rapid and continual nucleation followed by accelerated growth. We deposited Zn(S,O,OH) thin films by CBD with HMTA as an additive (HMTA films) and compared them to standard films without the bath additive.…”

Section: ■ Introductionmentioning

confidence: 99%

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Adherent and Conformal Zn(S,O,OH) Thin Films by Rapid Chemical Bath Deposition with Hexamethylenetetramine Additive

Opasanont

Van

Kuba

et al. 2015

ACS Appl. Mater. Interfaces

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ZnS is a wide band gap semiconductor whose many applications, such as photovoltaic buffer layers, require uniform and continuous films down to several nanometers thick. Chemical bath deposition (CBD) is a simple, low-cost, and scalable technique to deposit such inorganic films. However, previous attempts at CBD of ZnS have often resulted in nodular noncontinuous films, slow growth rates at low pH, and high ratio of oxygen impurities at high pH. In this work, ZnS thin films were grown by adding hexamethylenetetramine (HMTA) to a conventional recipe that uses zinc sulfate, nitrilotriacetic acid trisodium salt, and thioacetamide. Dynamic bath characterization showed that HMTA helps the bath to maintain near-neutral pH and also acts as a catalyst, which leads to fast nucleation and deposition rates, continuous films, and less oxygen impurities in the films. Films deposited on glass from HMTA-containing bath were uniform, continuous, and 90 nm thick after 1 h, as opposed to films grown without HMTA that were ∼3 times thinner and more nodular. On Cu2(Zn,Sn)Se4, films grown with HMTA were continuous within 10 min. The films have comparatively few oxygen impurities, with S/(S+O) atomic ratio of 88%, and high optical transmission of 98% at 360 nm. The Zn(S,O,OH) films exhibit excellent adhesion to glass and high resistivity, which make them ideal nucleation layers for other metal sulfides. Their promise as a nucleation layer was demonstrated with the deposition of thin, continuous Sb2S3 overlayers. This novel HMTA chemistry enables rapid deposition of Zn(S,O,OH) thin films to serve as a nucleation layer, a photovoltaic buffer layer, or an extremely thin continuous coating for thin film applications. HMTA may also be applied in a similar manner for solution deposition of other metal chalcogenide and oxide thin films with superior properties.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Adherent and Conformal Zn(S,O,OH) Thin Films by Rapid Chemical Bath Deposition with Hexamethylenetetramine Additive

Opasanont

Van

Kuba

et al. 2015

ACS Appl. Mater. Interfaces

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] 그러나, 벌크재 료의 UV 여기발광(UV stimulated emission) 및 레이저 특성은 저온에서 관찰되므로, 상온에서 UV 여기발광특 성을 관찰하기 위해서는 크기효과(size effect)에 따른 양 자구속효과(quantum confinement effect)를 가질 수 있는 1차원 나노구조가 요구된다. …”

Section: 서 론unclassified

Growth and UV Emission of Preferred Oriented ZnO Nanowires Using Hydrothermal Process

Kim¹,

Lim²,

Kim³

et al. 2011

Korean. J. Mater. Res.

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1-D ZnO nanowires have been attractive for their peculiar properties and easy growth at relatively low temperature. The length, diameter, and density of ZnO nanowires were determined by the several synthetic parameters, such as PEI concentration, growth time, temperature, and zinc salt concentration. The ZnO nanowires were grown on the <001> oriented seed layer using the hydrothermal process with zinc nitrate and HMTA (hexamethylenetetramine) and their structure and optical properties were characterized. The morphology, length and diameter of the nanowires were strongly affected by the relative and/ or absolute concentration of Zn 2+ and OH −1 and the hydrothermal temperature. When the concentrations of the zinc nitrate HMTA were the same as 0.015 M, the length and diameter of the nanowires were 1.97 µm and 0.07 µm, respectively, and the aspect ratio was 28.1 with the preferred orientation along the <001> direction. XRD and TEM results showed a high crystallinity of the ZnO nanowires. Optical measurement revealed that ZnO nanowires emitted intensive stimulated UV at 376 nm without showing visible emission related to oxygen defects.

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“…[18][19][20] In this work, we compare the behavior of complexing agents by using a reference recipe that we recently developed for rapid deposition of low-oxygen ZnS films for photovoltaic buffer layer and nucleation layer applications. 20 The near-neutral chemistry has a different dominant deposition pathway than the typical ion reaction as described above, but the conclusions can be extended to any system that ions, 23 and thus does not complicate the modeling of speciation. Hence, the important concentrations in our comparison of complexing agents on the deposition rate are the total and free Zn 2+ ion concentrations, TAA concentration, and pH.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Speciation Modeling to Guide Selection of Complexing Agents for Chemical Bath Deposition: Case Study for ZnS Thin Films

Opasanont

Baxter

2015

Crystal Growth & Design

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The dynamic behavior of complexing agents often governs kinetics of chemical bath deposition (CBD), but dynamics are frequently overlooked in favor of a more simplified description of only initial conditions.Here we demonstrate the importance of complexing agent dynamics using a combination of equilibrium speciation modeling and experiments for the case of ZnS thin films grown with three common complexing agents: ethylenediaminetetraacetate (EDTA), nitrilotriacetate (NTA), and citrate, using a reference recipe that ensured fair comparison. Complexing agents control the deposition rate by limiting the availability of free cations. Speciation modeling was used to simulate the free Zn 2+ concentration as a function of total Zn 2+ for baths with the individual agents. Based on the primary stability constants, deposition rate was predicted to decrease abruptly with reaction time for the EDTA bath, whereas baths with NTA or citrate should provide deposition rates that decrease only slightly over time. The predicted deposition profiles of the three baths were observed experimentally using a continuous-flow microreactor for CBD and were supported by the measured total Zn 2+ concentration profiles. Understanding and predicting the dynamic behavior of complexing agents by simulation enables strategic design of CBD processes for many material systems.

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In Situ X-ray Absorption Near-Edge Structure Spectroscopy of ZnO Nanowire Growth During Chemical Bath Deposition

Cited by 64 publications

References 50 publications

Adherent and Conformal Zn(S,O,OH) Thin Films by Rapid Chemical Bath Deposition with Hexamethylenetetramine Additive

Adherent and Conformal Zn(S,O,OH) Thin Films by Rapid Chemical Bath Deposition with Hexamethylenetetramine Additive

Growth and UV Emission of Preferred Oriented ZnO Nanowires Using Hydrothermal Process

Dynamic Speciation Modeling to Guide Selection of Complexing Agents for Chemical Bath Deposition: Case Study for ZnS Thin Films

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