Charge doping and large lattice expansion in oxygen-deficient heteroepitaxial WO3

Abstract

Tungsten trioxide is a versatile material with widespread applications ranging from electrochromic and optoelectronic devices to water splitting and catalysis of chemical reactions. For technological applications, thin films of WO3 are particularly appealing, taking advantage from high surface-to-volume ratio and tunable physical properties. However, the growth of stoichiometric, crystalline thin films is challenging because the deposition conditions are very sensitive to the formation of oxygen vacancies. In this work, we show how background oxygen pressure during pulsed laser deposition can be used to tune the structural and electronic properties of WO3 thin films. By performing X-ray diffraction and low-temperature transport measurements, we find changes in WO3 lattice volume up to 10%, concomitantly with an insulator-to-metal transition as a function of increased level of electron doping. We use advanced ab initio calculations to describe in detail the properties of the oxygen vacancy defect states, and their evolution in terms of excess charge concentration. Our results depict an intriguing scenario where structural, electronic, optical, and transport properties of WO3 single-crystal thin films can all be purposely tuned by a suited control of oxygen vacancies formation during growth.

References in corpus (5)

• First-principles re-investigation of bulk WO3
• Epitaxial growth and thermodynamic stability of SrIrO3/SrTiO3 heterostructures
• Ordering and multiple phase transitions in ultra-thin nickelate superlattices
• Insulator to metal transition of WO3 epitaxial films induced by electrochemical Li-ion intercalation
• Epitaxial growth of hexagonal tungsten bronze CsxWO3 films in superconducting phase region exceeding bulk limit

Cited by in corpus (4)

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• Large tunability of strain in WO3 single-crystal microresonators controlled by exposure to H2 gas
• Strain, Young's modulus, and structural transition of EuTiO3 thin films probed by micro-mechanical methods
• Orbital Hybridization Induces Giant Cubic Rashba Effect at Cu/WO${}_3$ Interface