Plasma Processing of Sapphire Nanostructures for Low-Loss Multilayer Composites
Abstract
Major Goals: Multilayer materials consisting of alternating ceramic and polymer layers are commonly found in naturally occurring nacre shell, and can find application as lightweight armor. However, such an architecture is generally opaque, and suffers from thin-film interference effects that lead to iridescence. Recent work by our group demonstrated that such optical limitations can be overcome by using interfacial nanostructures in silica-polymer multilayers, resulting in enhancement of optical transmission and suppression of iridescent effects [9,10]. However, challenges remain: (1) While the principle was demonstrated using silica, hard ceramics such as Al2O3 (sapphire) and AlON are more suitable for armor applications. These materials have higher refractive indices that can lead to higher optical losses. (2) Sapphire also has high mechanical hardness and is chemically stable, making it more resistant to micromachining. This can lead to challenges in controlling the profile of the interfacial nanostructures The proposed research aims to investigate the plasma processing of sapphire and create surface nanostructures with well-defined geometry and order. Sapphire and other aluminum oxide materials have high optical transmission, mechanical hardness, strength, and toughness, and are attractive for armor material, nanophotonics, and solid-state lighting. However, they are also chemically inert and can be difficult to micromachining, especially for high density features. This research will examine the etching dynamics and physical/chemical reactions of nanostructured sapphire. We will develop novel lithographic and plasma etching processes to enable precise control of structure geometry and order. Furthermore, we will use the sapphire nanostructures as a basic building block to suppress reflection losses, iridescence, and scattering to enhance transmission of multilayer sapphire-polymer composites.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 08, 2018
- Accession Number
- AD1068802
Entities
People
- Chih-Hao Chang
Organizations
- North Carolina State University