Performance studies of thin film electroluminescent (TFEL) devices

Sethu, M., 2002. Performance studies of thin film electroluminescent (TFEL) devices. PhD, Nottingham Trent University.

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Abstract

The study of mechanisms that contribute to the characteristics of Alternating Current Thin Film Electroluminescent (ACTFEL) display devices are presented. Primarily the investigation is based on Y2O3 thin film insulator, ZnS:Mn thin film phosphor and ACTFEL devices, which were fabricated by radio frequency magnetron sputtering with the effects of deposition parameters, post deposition annealing temperature, and source material. An extensive study was performed of the thin film Y2O3 grown on silicon (100) substrate for its role as a high dielectric constant insulator material. The reproducibility problem associated with this thin film material was addressed whereby the lifetime of the sputtering target was identified to be a contributing factor. The crystallite structural growth of the oxide is empirically compared with its charge properties. In general, the interface state density between the sputtered Y2O3 and Silicon has a high value, extending to 1013 cm-2 eV-1 in some discrete state, however the density was significantly reduced by thermal treatment in vacuum. Thin film ZnS:Mn deposited at 200 °C substrate temperature has the best crystallinity both on Silicon and on Y2O3 thin film and hence has the best phosphor efficiency. Additionally, annealing the thin film also improved the phosphor efficiency, unlocking the true potential of the phosphor, which was mainly due to an increase in number of radiative sites. The interfacial charge density and distribution at the interface of the insulator/phosphor is shown to be critical in determining the operation characteristics of the ACTFEL device whereby annealing and ageing affects it. Devices annealed at 400°C had the most stable ageing behaviour. SiON insulator ACTFEL device exhibited a large positive shift in LV characteristics, which was primarily due to a decrease in SiON layer capacitance. Both Y2O3 and SiON insulators ACTFEL device have advantages and disadvantages associated with their use.

Item Type:	Thesis
Creators:	Sethu, M.
Date:	2002
ISBN:	9781369313826
Identifiers:	Number Type PQ10183101 Other
Divisions:	Schools > School of Science and Technology
Record created by:	Linda Sullivan
Date Added:	17 Sep 2020 14:23
Last Modified:	13 Jul 2023 10:07
URI:	https://irep.ntu.ac.uk/id/eprint/40769

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