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

Abstract

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.

23.6%-efficient monolithic perovskite/silicon tandem solar cells with improved stability

“…The X-ray photoelectron spectroscopy (XPS) sputter depth profile of the 4 nm SnO2/2 nm ZTO stack in Supplementary Figure 4 shows only partial diffusion of zinc into the tin oxide film, indicating that 4 nm of SnO2 is sufficient to prevent detectable concentrations of zinc from reaching the perovskite. ZTO was deposited by combining SnO2 and ZnO ALD processes in a repeating supercycle consisting of three cycles of SnO2 followed by three cycles of ZnO 43,44 . The parameters for the individual SnO2 and ZnO processes used in the ZTO supercycle are described in Supplementary Tables 1-4.…”

Synthesis of Doped, Ternary, and Quaternary Materials by Atomic Layer Deposition: A Review

“…253,254 An example of these unfavorable effects as a result of large bilayers can be seen where the effect of the bilayer period on the crystallographic phase after annealing at 800 °C was investigated. 253 It was found that large bilayer periods lead to crystalline regions of ZnO and SnO 2 but that films with shorter bilayer periods showed mostly ternary Zn 2 SnO 4 diffraction patterns, the expected phase at this annealing temperature. The results highlight the importance of intermixing, by demonstrating that films with larger bilayer periods can crystallize into distinct phases (resembling Case 1 in Figure 8) rather than a single mixed phase.…”

Incomplete elimination of precursor ligands during atomic layer deposition of zinc-oxide, tin-oxide, and zinc-tin-oxide

“…Hultqvist et al applied the material as a buffer layer in CIGS solar cells, 14,15 Heo et al investigated its use as a channel material in amorphous oxide thin film transistors, 16 and our previous work was motivated by the potential application of ZTO as a transparent conducting oxide (TCO) for solar cells. 7,17 In a previous study, it was reported that ZTO is deposited by ALD with a lower growth rate than would be expected based on the binary growth rates of SnO 2 ALD from TDMASn and H 2 O (0.70 Å/cycle at 150…”