Synthesis of γ‐WO₃ thin films by hot wire‐CVD and investigation of its humidity sensing properties

Abstract

In this study, monoclinic tungsten oxide (γ‐WO3) have been grown in a single step using HW‐CVD method by resistively heating W filaments in a constant O2 pressure. The formation of γ‐WO3 was confirmed using low angle‐XRD and Raman spectroscopy analysis. Low angle‐XRD analysis revealed that as‐deposited WO3 film are highly crystalline and the crystallites have preferred orientation along the (002) direction. HRTEM analysis and SAED pattern also show the highly crystalline nature of WO3 with d spacing of ∼ 0.38 nm, having an orientation along the (002) direction. Surface topography investigated by SEM analysis shows the formation of a uniform and homogeneous cauliflower like morphology throughout the substrate surface without flaws and cracks. A humidity sensing device incorporating WO3 is also fabricated, which shows a maximum humidity sensitivity factor of ∼ 3954% along with a response time of ∼14 s and a recovery time of ∼25 s. The obtained results demonstrate that it is possible to synthesize WO3 in a single step by HW‐CVD method and to fabricate a humidity sensor by using it.

Electrodeposition of PEDOT:ClO4 on non-noble tungsten microwire for nerve and brain recordings

“…A non-burned W-microwire – only stripped – was used as control. The chemical reaction for the burning step could be estimated as follow: 65 2W (solid) + 3O 2 (gas) → 2WO 3 (thin film coating)…”

Low-temperature open-atmosphere growth of WO3 thin films with tunable and high-performance photoresponse

“…[26][27][28][29] High-quality oriented WO 3 thin films can be made by CVD, although this typically requires the use of single crystal substrates or high-temperature and lowatmospheric conditions. [30][31][32] Other chemical/solution processes can be used to achieve oriented WO 3 films, e.g., electrodeposition, anodization, hydrothermal and solvothermal reactions. However, solution processes can be less reproducible than physical processes, and high-temperature post-annealing (4500 1C) is often required to give good performance.…”

“…26–29 High-quality oriented WO 3 thin films can be made by CVD, although this typically requires the use of single crystal substrates or high-temperature and low-atmospheric conditions. 30–32 Other chemical/solution processes can be used to achieve oriented WO 3 films, e.g. , electrodeposition, anodization, hydrothermal and solvothermal reactions.…”

Implementación de un sistema de depósito químico en fase vapor asistido por filamento caliente (HFCVD) para la obtención del semiconductor trióxido de tungsteno (WO3)

“…Es un material polimórfico que cristaliza en diferentes fases dependiendo de la metodología de crecimiento y la temperatura; entre ellas están: monoclínica, triclínica, ortorrómbica y tetragonal [11], [12]. Puede presentar propiedades electrocrómicas, catalíticas y fotocatalíticas [13], [14], siendo estas utilizadas en diferentes aplicaciones como en la detección de gases, degradación de contaminantes orgánicos, fotocatálisis, dispositivos fotocromáticos, almacenamiento de energía, dispositivos optoelectrónicos, microelectrónica, memoria óptica, etcétera [15], [16], [17], [18]. El desarrollo de nuevos métodos sintéticos para producir WO3 han sido un enfoque importante en el campo de la investigación.…”