Date of Graduation

2015

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Konstantinos A Sierros

Committee Co-Chair

Samir N Shoukry

Committee Member

Charter D Stinespring

Abstract

Micro scale patterning of transparent conducting oxide (TCO) offers great promise in producing efficient and low cost devices. Most of the major patterning techniques are either complex, expensive, non-scalable, or involve the use of environmentally unfriendly chemicals. Therefore, patterning of Aluminum doped Zinc Oxide (AZO) via sol-gel route, combined with direct writing, in particular, nozzle-based robotic deposition, offers a relatively easy and efficient way to selectively deposit complex features in digitally precise locations, at low cost and without excessive use of harmful chemicals. However, the printing process involves the interplay of various parameters, which need to be properly related, in order to annex the inherent benefits in the manufacturing process.;Hence, the focus of this work is to investigate the influence of the printing parameters, which are viscosity, nozzle size, extrusion pressure, dispensing height and writing speed on the properties of the patterned AZO feature on glass substrates. The properties of interest include geometry of deposited and sintered feature, morphology, microstructure and electrical conductivity. A dual, three factors, three levels factorial experiment was designed to determine the influence of the printing parameters on the feature geometry. The morphology and crystal structure of the sintered feature at various combinations of printing parameters were studied by scanning electron microscopy (SEM) and x-ray diffraction (XRD). Also, the electrical properties of sintered feature with and without ultraviolet (UV) light irradiation were determined in a metal-semiconductor-metal configuration using a semiconductor analyzer.;It was found that the main effects and interactions among the printing parameters considered were significant in determining the spread and the profile of the deposited features at 95% confidence level. A link between the printing parameters and the morphology and crystal structure was established, providing the opportunity for tailoring the deposited film to desired end use, without altering the chemical composition or post processing treatment. The electrical property, which increased upon UV excitation, was also found to be comparable with those reported in the literature for conventionally sol-gel deposited AZO films.;Given the achieved control of feature geometry and microstructure through alteration of printing parameters, and the electrical conductivity of the deposited patterns, this work provides a pathway to efficient, large area optoelectronic devices at low cost.

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