Tailoring CuO_x Films via Open-Air Spatial Atomic Layer Deposition and Their Application in Room-Temperature Humidity...

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Copper oxide (CuO_x) is a promising material for various electronic applications.
• Controlling the properties of CuO_x thin films is crucial for device performance.
• Open-air atmospheric-pressure spatial atomic layer deposition (AP-SALD) offers a scalable method for thin film synthesis.

Purpose of the Study:

• To demonstrate the tunability of CuO_x thin films synthesized via AP-SALD.
• To investigate the effects of deposition temperature, precursor flow rate, and nitrogen doping on film properties.
• To evaluate the performance of tailored CuO_x films in chemiresistive humidity sensors.

Main Methods:

• Systematic variation of deposition temperature and copper precursor flow rate.
• In situ nitrogen doping using ammonium hydroxide as an oxidant.
• Characterization of film properties including crystallinity, oxidation state, composition, carrier concentration, and resistivity.
• Fabrication and testing of interdigitated-electrode humidity sensors.

Main Results:

• Achieved very low resistivity (0.178 Ω·cm) and high carrier concentration (10¹⁹ cm^-3) in optimized CuO_x films.
• Demonstrated successful modulation of film properties through controlled deposition and doping.
• Developed CuO_x-based humidity sensors with a limit of detection of 99 ppm and sensitivity of 0.244 Ω·ppm^-1 at room temperature.

Conclusions:

• AP-SALD is a powerful technique for tailoring CuO_x film properties.
• Controlled deposition and in situ doping enable application-specific optimization.
• This work paves the way for advanced optoelectronic and sensing platforms using tunable CuO_x films.