How to obtain an electrochromic layer of tungsten oxides of the stoicheometric composition WO3. What are the optimal deposition conditions?
Use tungsten sputtering target by adjusting the parameter of power, argon:oxygen flowrate and distance between substrate and target. Try between 10-30 ml/min of oxygen flowrate at 200 W.
Dear Mrs. Syahirah Zakria thank you very much for your answer. Please tell me what ratio of oxygen: argon needs to be pumped into the magnetron chamber?
To apply electrochromic WO3 films to ITO glass using reactive magnetron sputtering, you can follow the procedure outlined in a research article 1. The article describes the deposition of WO3–Nb2O5 electrochromic films and an ITO/WO3–Nb2O5/Nb2O5/NiVOx/ITO all-solid-state electrochromic device using fast-alternating bipolar-pulsed magnetron sputtering with tungsten and niobium targets. The article discusses the influence of different sputtering powers from the niobium target on the refractive index, extinction coefficient, optical modulation, coloration efficiency, reversibility, and durability of the WO3–Nb2O5 films. The aim of the study is to find the suitable Nb proportion to increase durability and less negative effect in the electrochromic performance of Nb2O5-doped WO3 films. The lifetime of the WO3–Nb2O5 films is 4 times longer than pure WO3 films when the sputtering power of the Nb target is higher than 250 W. The results show that WO3–Nb2O5 composite films used for an all-solid-state electrochromic device can sustain over 3 × 10^4 repeated coloring and bleaching cycles while the transmission modulations can be kept above 20%. The coloring and bleaching response times are 7.0 and 0.7 s, respectively.
I hope this information helps! Let me know if you have any other questions.
1: MDPI
Applying electrochromic tungsten trioxide (WO₃) films to indium tin oxide (ITO) glass using reactive magnetron sputtering involves several steps. Reactive sputtering allows for the deposition of thin films with controlled stoichiometry. Here is a general guide for the process:
Materials and Equipment:
Procedure:
1. Substrate Preparation:
- Clean the ITO glass substrates thoroughly using a suitable cleaning method (e.g., ultrasonic cleaning in acetone and isopropanol).
- Ensure that the substrates are free from contaminants, grease, and particles.
2. Sputtering Chamber Preparation:
- Load the cleaned ITO substrates into the sputtering chamber using a suitable substrate holder.
- Install the tungsten (W) target in the sputtering system.
3. Pumping and Venting:
- Pump down the chamber to achieve a high vacuum.
- Introduce a small amount of argon gas to establish a sputtering atmosphere.
4. Reactive Sputtering:
- Adjust the sputtering parameters:Set the power on the W target (DC or RF power). Control the argon gas flow rate. Introduce a controlled flow of oxygen gas for reactive sputtering. The oxygen flow rate will influence the film stoichiometry. Optimize the deposition pressure for efficient sputtering.
5. Film Deposition:
- Initiate the sputtering process to deposit the WO₃ film onto the ITO glass substrate.
- Monitor the film thickness in real-time using a suitable deposition rate monitor or a quartz crystal microbalance.
6. Annealing (Optional):
- Optionally, perform post-deposition annealing to enhance the film properties. Annealing can improve crystallinity and electrochromic performance.
7. Characterization:
- Characterize the deposited films using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) to assess film structure and morphology.
8. Electrochromic Testing:
- Test the electrochromic properties of the WO₃ film on the ITO glass. This involves applying a voltage to the film and observing the color changes.
9. Encapsulation (Optional):
- If necessary, encapsulate the electrochromic device to protect it from environmental factors.
Notes:
- It's important to carefully control the oxygen flow rate during reactive sputtering to achieve the desired stoichiometry in the WO₃ film.
- Adjust the deposition parameters based on the specific requirements of the electrochromic device and desired film properties.
This is a general guide, and the exact parameters may vary based on the specific equipment used, target material, and desired film characteristics. It's recommended to refer to the equipment manual and literature on reactive magnetron sputtering for more detailed information. Additionally, safety precautions should be followed when working with vacuum systems and sputtering gases.
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