The effect of substrate temperature on atomic layer deposited zinc tin oxide

Lindahl, Johan; Hägglund, Carl; Wätjen, Jörn Timo; Edoff, Marika; Törndahl, Tobias

doi:10.1016/j.tsf.2015.04.029

Cited by 47 publications

(39 citation statements)

References 27 publications

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“…The Sn/(Sn + Zn) cycle fraction during the 650 ALD cycles was set to 0.5, resulting in an atomic ratio of [Sn]/([Zn] + [Sn]) ~0.2 in the final film. For further details of the ALD process, we refer to Keller et al and Lindahl et al…”

Section: Experimental and Computational Methodsmentioning

confidence: 99%

Wide‐gap (Ag,Cu)(In,Ga)Se₂ solar cells with different buffer materials—A path to a better heterojunction

Keller

Sopiha

Stolt

et al. 2020

Progress in Photovoltaics

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139

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This contribution concerns the effect of the Ag content in wide‐gap AgwCu1‐wIn1‐xGaxSe2 (ACIGS) absorber films and its impact on solar cell performance. First‐principles calculations are conducted, predicting trends in absorber band gap energy (Eg) and band structure across the entire compositional range (w and x). It is revealed that a detrimental negative conduction band offset (CBO) with a CdS buffer can be avoided for all possible absorber band gap values (Eg = 1.0–1.8 eV) by adjusting the Ag alloying level. This opens a new path to reduce interface recombination in wide‐gap chalcopyrite solar cells. Indeed, corresponding samples show a clear increase in open‐circuit voltage (VOC) if a positive CBO is created by sufficient Ag addition. A further extension of the beneficial compositional range (positive CBO at buffer/ACIGS interface) is possible when exchanging CdS with Zn1‐ySnyOz, because of its lower electron affinity (χ). Nevertheless, the experimental results strongly suggest that at present, residual interface recombination still limits the performance of solar cells with optimized CBO, which show an efficiency of up to 15.1% for an absorber band gap of Eg = 1.45 eV.

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Section: Experimental and Computational Methodsmentioning

confidence: 99%

Wide‐gap (Ag,Cu)(In,Ga)Se₂ solar cells with different buffer materials—A path to a better heterojunction

Keller

Sopiha

Stolt

et al. 2020

Progress in Photovoltaics

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139

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“…Here the ZTO‐layers are deposited by atomic layer deposition (ALD), since this makes it possible to vary the bandgap of the films by changing Sn/(Zn + Sn)‐ratio or process temperature. This enables optimization of the band alignment with the absorber . In this paper we focus on varying the process temperature, which was also done in our previous paper, however in that case, lower temperatures were used, and the buffer layer composition and thickness fluctuated .…”

Section: Introductionmentioning

confidence: 99%

Zinc‐Tin‐Oxide Buffer Layer and Low Temperature Post Annealing Resulting in a 9.0% Efficient Cd‐Free Cu₂ZnSnS₄ Solar Cell

Ericson¹,

Larsson²,

Törndahl³

et al. 2017

Solar RRL

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Zn 1-x Sn x O y (ZTO) has yielded promising results as buffer material for the full sulfur Cu 2 ZnSnS 4 (CZTS), with efficiencies continuously surpassing its CdS-references. ZTO can be deposited by atomic layer deposition (ALD) enabling tuning of the conduction band position through choice of metal ratio or deposition temperature. Thus an optimization of the conduction band alignment between ZTO and CZTS can be achieved. The ZTO bandgap is generally larger than that of CdS and can therefore yield higher currents due to reduced losses in the short wavelength region. Another advantage is the possibility to omit the toxic Cd. In this study the ALD process temperature was varied from 105 to 165 °C. Current-blocked devices were obtained at 105 °C while the highest open-circuit voltage and device efficiency was achieved for 145 °C. The highest fill factor was seen at 165 °C. The best efficiency reached in this study was 9.0 %, which, to our knowledge, is the highest efficiency reported for Cd-free full-sulfur CZTS. We also show that the effect of heat needs to be taken into 2 account. The results indicate that part of the device improvement comes from heating the absorber, but that the benefit of using a ZTO-buffer is clear.

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“…This results in a morphology for short bilayer periods (<20 cycles) characterized by ZnO inclusions (islands, clusters) in a SnO x matrix, in line with recent TEM observations. 11 For bilayer periods exceeding approximately 20 cycles, more discrete layers are formed. There are no clear indications of atomic scale mixing and formation of a solid solution for ZTO stacks grown by ALD at 150 C; however, postannealing at 400 C creates a stable surface phase with equal amounts of Zn and Sn in the outermost atomic layer.…”

Section: Discussionmentioning

confidence: 99%

“…After repeated supercycles this leads to a film of ZnO nanoparticles in a SnO x matrix, which is further in line with recent observations by TEM for a related system. 11 At some point between 15 and 50 ZnO sublayer cycles, however, ZnO film closure is observed and a laminated ZnOSnO x structure then results. In both cases, the mixing of the two phases occurs on the nanoscale rather than on the atomic scale.…”

Section: -mentioning

confidence: 99%

“…To this end, the production of ZTO of varying (average) stoichiometry has previously been investigated by stacking thin ZnO and SnO x layers by low temperature ALD. [9][10][11] In this way, a homogeneous ternary compound has been approached by repeating a supercycle of the individual Zn and Sn oxide ALD sequences. The atomic scale control of the oxide sublayer thicknesses provided by the design of the supercycle allows for fine tuning the compound properties toward specific conditions.…”

Section: Introductionmentioning

confidence: 99%

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Growth, intermixing, and surface phase formation for zinc tin oxide nanolaminates produced by atomic layer deposition

Hägglund

Grehl²,

Tanskanen

et al. 2016

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A broad and expanding range of materials can be produced by atomic layer deposition at relatively low temperatures, including both oxides and metals. For many applications of interest, however, it is desirable to grow more tailored and complex materials such as semiconductors with a certain doping, mixed oxides, and metallic alloys. How well such mixed materials can be accomplished with atomic layer deposition requires knowledge of the conditions under which the resulting films will be mixed, solid solutions, or laminated. The growth and lamination of zinc oxide and tin oxide is studied here by means of the extremely surface sensitive technique of low energy ion scattering, combined with bulk composition and thickness determination, and x-ray diffraction. At the low temperatures used for deposition (150 C), there is little evidence for atomic scale mixing even with the smallest possible bilayer period, and instead a morphology with small ZnO inclusions in a SnO x matrix is deduced. Postannealing of such laminates above 400 C however produces a stable surface phase with a 30% increased density. From the surface stoichiometry, this is likely the inverted spinel of zinc stannate, Zn 2 SnO 4 . Annealing to 800 C results in films containing crystalline Zn 2 SnO 4 , or multilayered films of crystalline ZnO, Zn 2 SnO 4 , and SnO 2 phases, depending on the bilayer period.

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The effect of substrate temperature on atomic layer deposited zinc tin oxide

Cited by 47 publications

References 27 publications

Wide‐gap (Ag,Cu)(In,Ga)Se₂ solar cells with different buffer materials—A path to a better heterojunction

Wide‐gap (Ag,Cu)(In,Ga)Se₂ solar cells with different buffer materials—A path to a better heterojunction

Zinc‐Tin‐Oxide Buffer Layer and Low Temperature Post Annealing Resulting in a 9.0% Efficient Cd‐Free Cu₂ZnSnS₄ Solar Cell

Growth, intermixing, and surface phase formation for zinc tin oxide nanolaminates produced by atomic layer deposition

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The effect of substrate temperature on atomic layer deposited zinc tin oxide

Cited by 47 publications

References 27 publications

Wide‐gap (Ag,Cu)(In,Ga)Se2 solar cells with different buffer materials—A path to a better heterojunction

Wide‐gap (Ag,Cu)(In,Ga)Se2 solar cells with different buffer materials—A path to a better heterojunction

Zinc‐Tin‐Oxide Buffer Layer and Low Temperature Post Annealing Resulting in a 9.0% Efficient Cd‐Free Cu2ZnSnS4 Solar Cell

Growth, intermixing, and surface phase formation for zinc tin oxide nanolaminates produced by atomic layer deposition

Contact Info

Product

Resources

About

Wide‐gap (Ag,Cu)(In,Ga)Se₂ solar cells with different buffer materials—A path to a better heterojunction

Wide‐gap (Ag,Cu)(In,Ga)Se₂ solar cells with different buffer materials—A path to a better heterojunction

Zinc‐Tin‐Oxide Buffer Layer and Low Temperature Post Annealing Resulting in a 9.0% Efficient Cd‐Free Cu₂ZnSnS₄ Solar Cell