In-Situ Characterization of Metal-Oxide Films Deposited by Atmospheric-Pressure Spatial ALD—Deposition, Properties and Post-Deposition Performance Studies

Atmospheric-pressure spatial ALD (AP-SALD) is a rapid, scalable, open-air method for the deposition of thin films with nanoscale thickness control. We employ in-situ characterization to monitor the properties of ZnO and AlOx films during their deposition by by AP-SALD. Custom-made printed circuit boards and reflectance spectroscopy provide information about electrical and optical properties during the film growth. Both also provide insight into film nucleation. For fibrous substrates like textiles, a Virtual Interface model is used for in-situ estimation of the thickness of conformal shells formed on the substrate fibers. In-situ reflectance spectroscopy is also leveraged to provide feedback to the deposition system, enabling accurate control of the deposition rate. The conformal, pinhole-free nature of the AP-SALD films makes them promising for encapsulation applications. We develop machine-learning-enabled imaging methods to characterize the encapsulation performance of AP-SALD AlOx films when they are exposed to high humidities during calcium transmission-rate tests and perovskite solar cell degradation tests.