Growth and characterization of ZnO thin films at low temperatures: from room temperature to − 120 °C
Entity
UAM. Departamento de Física Aplicada; UAM. Departamento de Física de MaterialesPublisher
ElsevierDate
2021-07-06Citation
10.1016/j.jallcom.2021.161056
Journal of Alloys and Compounds 884 (2021): 161056
ISSN
0925-8388 (print)DOI
10.1016/j.jallcom.2021.161056Funded by
This investigation has been funded by the Ministerio de Ciencia, Innovación y Universidades of Spain through the FIS2015-67367-C2- 1-P project and by the Comunidad de Madrid through the NANOMAGCOST-CM P2018/NMT4321 project. One of the authors (C.M.) thanks Ministerio de Educación, Cultura y Deportes for FPU014/02020 grantProject
Gobierno de España. FIS2015-67367-C2-1-P; Comunidad de Madrid. S2018/NMT-4321/NANOMAGCOST-CMEditor's Version
https://doi.org/10.1016/j.jallcom.2021.161056Subjects
DRX; Electrical properties; Morphology; Optical properties; SEM; Thin films; ZnO; FísicaRights
© 2021 Universidad Autónoma de MadridEsta obra está bajo una licencia de Creative Commons Reconocimiento-NoComercial-SinObraDerivada 4.0 Internacional.
Abstract
ZnO thin films have been grown by e-beam evaporation in the range from room temperature to − 120 °C on two types of substrates, Al2O3 (0001) and Si (100). Although the ZnO/Al2O3 system has been thoroughly characterized, including optical and electrical techniques, the morphological, structural and chemical properties show no significant differences between both substrates. Thus, the general features of the ZnO growth mode at low temperature can be generalized. The relatively low growth temperatures reduce the diffusion of atoms at the surface, which leads to morphological and chemical changes. As the temperature decreases, the growth mode changes from a van der Drift model to a gradual bilayer system composed of an interfacial layer in contact with the substrate and a second columnar-based layer. This second well-ordered film disappears for the lowest temperatures while a Zn-rich interface in contact with the substrate emerges. Precisely from this interface, Zn-rich whiskers develop under the ZnO film and cause the loss of adhesion at temperatures below − 100 °C. These extreme temperatures also affect the crystal size, lattice strain, and total amount of oxygen vacancies. The behavior of the optical and electrical properties in terms of band gap, transparency, electrical resistivity, and Seebeck coefficient is discussed in the light of structural and chemical characterization. Samples grown at 0 °C exhibit an enhanced transmittance compared to those grown at room temperature while preserving similar electrical resistivity values and natural n-type doping. These results open a promising route to enhance ZnO films properties below the typical high temperature window
Files in this item
Google Scholar:Morales, Carlos
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Leinen, Dietmar
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del Campo, Adolfo
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Ares Fernández, José Ramón
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Sánchez López, Carlos
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Flege, Jan Ingo
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Gutiérrez, Alejandro
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Prieto Recio, María Pilar
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Soriano Guillén, Leandro
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