Increasing the performance of thin film electroluminescent (TFEL) devices

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Craven, M.R., 2000. Increasing the performance of thin film electroluminescent (TFEL) devices. PhD, Nottingham Trent University.

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Abstract

Novel laterally emitting thin film electroluminescent (LETFEL) devices have been deposited, fabricated and characterised. The new device utilises BaTiO3 thin film insulators, exhibiting a higher dielectric constant over previously reported Y2O3 thin film insulators. A study into the effect of the deposition and post deposition annealing conditions on the characteristics exhibited by the BaTiO3 thin films is presented. This study has shown that the optimum growth conditions for BaTiO3 thin films deposited by RF magnetron sputtering are a substrate temperature of 200 °C in an atmosphere of 30 % oxygen in argon at 7 mT at 2.62 Wcm-2 with a post-deposition anneal at 700 °C for 1 hour. These deposition conditions produce a film with a dielectric constant of 26, a refi-active index of 2.1, a breakdown strength of 2.5 MV cm-1 and a charge storage capacity of 5.5 °C cm-2. LETFEL devices were characterised and exhibited a maximum luminance of 270,000 fL (driven with a 250 V ground to peak 5 KHz sine wave), this is, to the author's knowledge, the highest reported luminance for any thin film AC TFEL device. The improvement in luminance has been shown to be related to the increase in light confinement achieved by increasing the thickness of the cladding (insulator) in the device structure. An optical model for this improvement is presented.

Finally, the fabrication route for the LETFEL device has been updated to reduce miss-alignment and delivery delays and to allow the shaping of the aperture utilising ion milling.

Item Type:

Thesis

Creators:

Craven, M.R.

Date:

2000

ISBN:

9781369312997

Identifiers: