Invited Paper EM+AN+MI+SS-WeM1
Few Monolayer Atomic Layer Deposition (ALD) to Engineer New Surfaces and Interfaces

Wednesday, October 24, 2018, 8:00 am, Room 101A

Atomically precise modification of surfaces and interfaces with few monolayer material leads to improved understanding and significant enhancements in properties, performance and reliability of heterogeneous materials and devices. This talk highlights the impact of few monolayer insulators, wide bandgap semiconductors and metals, deposited using atomic layer deposition (ALD) on a variety of surfaces and interfaces with direct relevance to electronic and photonic devices.

The first part of this talk deep dives into the process science of ALD in its early cycles. The nature and structure of few monolayer ALD films is highlighted. In particular, configurational state and entropy of adlayers during every half-cycle of ALD¹ is exploited to exquisitely manipulate nucleation and growth of metallic Ru thin films.²

In the second part of this talk, applied aspects of few monolayer engineering of surfaces and interfaces is discussed. Case studies included are the non-linear optical phenomena on Au-Al₂O₃ and Au-ZnO surfaces,³ high performance photocatalysts for CO₂ photoreduction,⁴ improved optoelectronic responses from surface passivated CuO nanowires⁵ and few monolayer Ta₂O₅ to improve reliability of electrochromic windows.⁶

Regardless of the application, ALD at its ultimate thickness limit holds true potential for surface and interface engineering. The control of this process appears to be remarkably simple and yet, has hidden complexities that continue to push the boundaries of discovery of new materials and concept devices.

Relevant references:

¹ Zhengning Gao, Fei Wu, Yoon Myung, Ruixiang Fei, Ravindra Kanjolia, Li Yang, and Parag Banerjee, J. Vac. Sci. Technol. A 34 (1), 01A143 (2016); Lei Shi, Zhengning Gao, Zhaonan Liu, Yoon Myung, and Parag Banerjee, Chem. Mater. 29 (13), 5458 (2017).

² Zhengning Gao, Duy Le, Ravindra Kanjolia, Charles Dezelah, Jacob Woodruff, Talat Rahman, and Parag Banerjee, Under review (2018).

³ Zhengning Gao, Mallik M.R. Hussain, Domenico de Ceglia, Maria A. Vincenti, Andrew Sarangan, Imad Agha, Michael Scalora, Joseph A. Haus, and Parag Banerjee, Appl. Phys. Lett. 111, 161601 (2017).

⁴ W-N. Wang, F. Wu, Y. Myung, D.M. Niedzwiedzki, H.S. Im, J. Park, Parag* Banerjee, and Pratim* Biswas, * co-corresponding authors, ACS Appl. Mater. Interfaces 7 (10), 5685 (2015).

⁵ Sriya Banerjee, Zhengning Gao, Fei Wu, Yoon Myung, and Parag Banerjee, Under Review (2018).

⁶ Yang Wang, Jongwook Kim, Zhengning Gao, Omid Zandi, Sungyeon Heo, Parag Banerjee, and Delia Milliron, Chem. Mater. 28, 7198 (2016).