Hannah Maret



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2016 Honorable Mention

Status of Main Author

Undergraduate Student


Material Science and Engineering


Strandwitz, Nicholas

Publication Date



Sapphire (α-Al2O3) thin films can have applications as optical and scratch-resistant coatings, as well as in microelectronics. Typical sapphire substrate fabrication requires the material be in the molten state at temperatures above 2000°C. This study examines the crystallization of amorphous atomic layer deposited (ALD) alumina thin films at low temperatures (950-1050°C) by seeded lateral epitaxy. Decoration of the film with sapphire nanoparticle seeds before annealing provides nucleation sites for crystal growth. The growth rate of these grains was observed to be direction dependent according to the orientation of the nanoparticles. We also show the dependence of crystal growth rate on substrate thickness and stress state.

Author Notes

Catherine Fletcher is a junior studying Environmental Engineering at Lehigh University. She has served the Office of First-Year Experience as a PreLUsion Leader, Camp Hawk Counselor, Camp Hawk Guide, and Evolution Peer Leader. Catherine has been involved in the revitalization of abandoned biosand filters project under the guidance of Dr. Kristen Jellison since May 2015. She has previously presented the intermediate results at the New England Graduate Student Water Symposium as well as the STEPS & Environmental Initiative Research Seminar last fall. Her future plans are to obtain a job in water treatment after graduation in 2017.

Seeded Lateral Epitaxy Rates for Alumina Thin Films: Influence of Substrate and Stress State