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Low-Temperature Epitaxy of Perovskite WO3 Thin Films under Atmospheric Conditions
Nives Štrkalj, along with her colleagues from the University of Cambridge, published an article in the journal Small Structures demonstrating the deposition of epitaxial perovskite WO3 films at low temperatures under atmospheric conditions. Epitaxy is achieved through an exothermic reaction of precursors with oxygen, stabilizing a hot zone near the substrate.
Low-Temperature Epitaxy of Perovskite WO3 Thin Films under Atmospheric Conditions
Zhuotong Sun, Ziyi Yuan, Ming Xiao, Simon M. Fairclough, Atif Jan, Giuliana Di Martino, Caterina Ducati, Nives Strkalj, Judith L. MacManus-Driscoll, Small Struct., 5: 2400089.
DOI: https://doi.org/10.1002/sstr.202400089
This study demonstrates open-air low-temperature epitaxy of WO3 films with an A-site vacant perovskite structure using atmospheric pressure spatial chemical vapor deposition (AP-SCVD). WO3 is an interesting system to study because it is compatible with CMOS technology and has a variety of electronic and structural states that enable a wide range of applications, many of which rely on the crystalline orientation of the films. Epitaxial WO3 films can be deposited by various methods on oxide substrates, but so far, depositions have been in vacuum or low-pressure conditions and, in most cases, at temperatures above 500°C.
In this work, high-quality epitaxial WO3 films were achieved using AP-SCVD in open air at 350°C. Epitaxy was demonstrated up to a thickness of 80 nm with growth rates of 5 nm/min on single-crystal (001)-oriented SrTiO3 substrates. The electrical resistivity of the films is comparable to previous reports for epitaxial WO3 films deposited in vacuum using conventional deposition techniques at 500°C. Furthermore, different strain states of the WO3 films were obtained by epitaxial growth on single-crystal perovskite substrates with matching lattice parameters. The deposition process was analyzed in terms of the exothermic heat release from the decomposition reaction of the W[CO]6 precursor localized above the substrate. AP-SCVD could represent a growth method for achieving low-temperature epitaxy for oxide materials with low costs and high deposition rates.
![Figure 1: Illustration of WO3 film growth using AP-SCVD. Enlarged view of the exothermic reaction between W[CO]6 and O2 releasing heat and providing additional energy to the deposition process.](http://www.ifs.hr/wp-content/uploads/2024/07/Figure2.png)
Figure 1: Illustration of WO3 film growth using AP-SCVD. Enlarged view of the exothermic reaction between W[CO]6 and O2 releasing heat and providing additional energy to the deposition process.