Seeded Crystallization of ALD Alumina Thin Films
Departments: Materials Science and Engineering Advisor: Nicholas Strandwitz
Sapphire (a-Al¬2O3) is valued for its hardness, transparency, and chemical stability. As a thin film, it is used for scratch-resistant and optical coatings, as well as for microelectronics. However, fabrication of sapphire substrates from the molten state requires temperatures above 2000°C. Through this study, we examine the transformation of amorphous, atomic layer deposited alumina into large-grained polycrystalline sapphire films at low temperatures via seeded lateral solid phase epitaxy. Atomic layer deposition (ALD) is a growth technique used to produce thin, conformal films of precise thicknesses. Alumina films generated using the trimethylaluminum (TMA) precursor are always amorphous. Therefore, many studies have focused on crystallization of these films through post deposition annealing. However, the impact of seeding on the crystallization behavior of ALD alumina has not been reported. We propose that by depositing nanoparticle sapphire seeds on the amorphous film before annealing, the nucleation barrier for crystal growth can be lowered. We also analyzed textural properties of films based on seed orientation.
About Hannah Maret:
Hannah Maret is a junior studying Materials Science and Engineering. She joined Professor Strandwitz’s research group in March 2014 and has particularly enjoyed the opportunity to use one of Lehigh’s scanning electron microscopes (SEM) to perform sample analysis. Hannah is not only interested in the science of materials, but also the aesthetics. This semester she is interning with the ArtsQuest Glass Studio. She is learning how to assist with production and is also working on a project to improve the studio’s mobile glass furnace. Outside of materials, Hannah is involved with Engr10 - Applied Engineering Computer Methods as a teaching assistant. She mentors two classes of students to learn and apply programming skills in solving engineering problems using Matlab and Arduino, a single-board microcontroller. In her free time, Hannah likes to play piano and otherwise spend time outside, especially if it involves skiing or hiking. Hannah plans to pursue her interest in materials in graduate school and hopes to eventually explore applications in sustainable energy.