| AVS 63rd International Symposium & Exhibition | |
| Thin Film | Friday Sessions |
| Session TF-FrM |
| Session: | CVD, ALD and Film Characterization |
| Presenter: | Ankit Singh, Georgia Institute of Technology |
| Authors: | A. Singh, Georgia Institute of Technology A. Perrotta, Eindhoven University of Technology, Netherlands S. Graham, Georgia Institute of Technology |
| Correspondent: | Click to Email |
Encapsulation of electronic devices using vacuum deposited moisture barrier films is a critical step for their protection and enhancement of lifetime. Devices like implantable devices, OLEDs, OPVs, thin film transistors and thin film solar cells are prone to rapid degradation through chemical reactions with surrounding gas or liquid media. Barrier layers help in avoiding direct exposure of these devices to their surrounding environment thus enhancing their lifetime. Several deposition techniques can be used for preparation of such layers. Atomic layer deposition (ALD) is known to be able to produce ultra-barrier films with water vapor transmission rates lesser than 10-4 g/m2/day. However, performance and reliability of ALD based barrier films is governed by their stability in corresponding environments where resistance to corrosion and material stability will remain a key parameter to their durability.
In this work, we explore the use of TiO2, HfO2, ZrO2, and Al2O3 ALD based barrier films in harsh conditions like high temperature and a range of chemical exposure. The barrier layers were coated over ZnO sensors in order to test their ability to protect the ZnO in harsh environments and can be detected optically using photoluminescence. The exposure included DI water, salt water, phosphate buffer saline solution and low pH (HCl) solution. Degradation in ZnO films was monitored by photoluminescence testing in order to track the decrease in PL signal with time. To compliment the PL study, electron microscopy and a detailed EIS study was conducted in order to understand the mechanism of ALD barrier degradation in different environments. Several of ALD based metal oxides have shown enhanced corrosion resistance outperforming aluminum oxide which showed the least resistance. Finally, application of these barrier layers in protection of organic electronics and inorganic solar cells has been demonstrated.