Authors

Derek Weisberg

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Comments

2014 Second Place; People's Choice

Status of Main Author

Undergraduate Student

Department

Material Science and Engineering

Advisor

Chan, Helen; Strandwitz, Nicholas

Publication Date

2014

Description

Sapphire, a crystalline type of alumina (Al2O3), is a ceramic compound with several industrial applications. It is commonly used as a substrate wafer for compound semiconductor growth and LED manufacturing. In addition, it is often used as an optical window due to its high degree of optical transparency. The growth of large grain or single crystal sapphire however, is a time- and energy-intensive process, motivating new growth techniques. This investigation develops alternative pathways to produce large grained sapphire films on a variety of substrates. Atomic layer deposition (ALD) is an emerging growth technique capable of deposition of amorphous alumina with precise thickness control. Annealing of amorphous alumina films typically requires very high temperatures and results in nanoscopic crystals. We have demonstrated that by placing nanoparticle sapphire seeds on the amorphous ALD alumina, crystallization can be induced at far lower temperatures, resulting in large grains (several microns in diameter). Crystallization was observed at temperatures as low as 900 °C. By measuring the growth rates of the crystals at various temperatures, the growth temperature and time can be optimized to produce fully polycrystalline sapphire films on a variety of substrates.

Author Notes

Kristen Mejia is a third year undergraduate student at Lehigh. She is pursuing a degree in IDEAS with concentrations in Environmental Engineering, Women gender Sexuality Studies, Health Medicine Society, and Political Science. Kristen is extremely active on campus as she is the recruitment and retention chair of Lambda Theta Alpha. She is a member of the Rossin Junior Fellows and well as the nominated Undergraduate Representative for Lehigh’s Engineering Dean Search Committee. She is a gryphon in Taylor House and also loves to dance with African Renaissance. Her passion for water and its international implications stems from her own family history and she is determined to continue working on these issues well into the future. Not only has research given her an avenue to continue delving into her passions, but she has also been able to discover a world of questions and answers that she will continue to help solve.

Seeded Lateral Epitaxy of ALD Alumina Thin Films

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