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Carrier dynamics and optical properties of the multilayered aluminum-doped zinc oxide metamaterial
Campbell, Bethany Nicole
Sundqvist, KyleBlomgren, Peter
In this work, the carrier dynamics and optical properties of the multilayered aluminum-doped zinc oxide (Al:ZnO/ZnO) metamaterial are investigated. Zinc oxide (ZnO) is a semiconductor with a wide band gap, making it useful for a variety of applications requiring a material that can withstand high power, such as in the development of solar panels. ZnO can be doped with Al by replacing some of the Zn, forming aluminum oxide (Al2O3) instead. Al:ZnO/ZnO belongs to a class of metamaterials called transparent conducting oxides (TCOs). As the name suggests, materials in this class are transparent and highly conductive. They are ever present in modern society, one of the most obvious examples being the screen of most cell phones. One of the most popular types of TCO is indium-tin-oxide (ITO). However, it is increasingly scarce and expensive, resulting in a push for more cost e↵ective materials, such as Al:ZnO. First, I investigate the time dynamics of the ultrafast photoluminescence based on a set of rate equations. These rate equations relate the concentrations of electrons, holes, and photons based on their probabilities of transition. I investigate the behavior of the ultraviolet and visible photoluminescence within 5 ns. Next, I investigate the potential for the Burstein-Moss e↵ect. If present, the Burstein-Moss e↵ect may result in a blue-shift towards shorter wavelengths of the Al:ZnO/ZnO photoluminescence. I use ellipsometry data from our samples created using pulsed laser deposition to deduce the indices of refraction and calculate the transmittance. I find that there is a comparable shift near the ultraviolet region. Finally, I investigate the near-infrared transmission of our samples created using atomic layer deposition. This proves to be non trivial. Our broadband source is absorbed by water vapor at our wavelengths of interest and the transmittance is calculated using Fresnel equations for isotropic media. Therefore, I am only able to draw broad conclusions. The result of this work will inform our future studies of mode confinement and pulse propagation.
San Diego State University
Master of Science (M.S.) San Diego State University, 2020
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