Feasibility of micro-mirror laterally-emitting thin-film electroluminescent devices for an opto-electronic integrated circuit

Theng, S.P.S., 2001. Feasibility of micro-mirror laterally-emitting thin-film electroluminescent devices for an opto-electronic integrated circuit. PhD, Nottingham Trent University.

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The design and development of micro-mirror Laterally-Emitting Thin-Film Electroluminescent (mmLETFEL) devices aiming at image bar array applications such as electrophotographic printing has been one of the main objectives for the Optical Device Engineering Group at The Nottingham Trent University. This thesis describes the work carried out in determining the potential and possibility of developing the current mmLETFEL technology as an integrated optical device. In particular, assessing the feasibility and commercial viability for a novel Opto-Electronic Integrated Circuit (OEIC) - the mmLETFEL device integrated with the corresponding drive circuitry.

The initial investigation explores the feasibility of the current LETFEL technology in producing sufficient emission for exposing a photoconductively charged photoreceptor. The luminance observed from the edge emission of a LETFEL test device, has been found to discharge a commercial photoconductive drum, at 50% gain, and at a print speed of 13 p.p.m.

The fabrication of mmLETFEL test devices that are suitable for integration has been successful. This includes pre-fabricating base electrodes of PolySi and TiW materials, defined prior to the deposition of the mmLETFEL structure, and with insulators of Y2O5 and Si3O4. Results from the electro-optical characterisation of these four configurations of mmLETFEL device structures have demonstrated that Y2O3 supersedes Si3N4 material as an appropriate dielectric, in that the Iuminance versus drive voltage (L-V) curve exhibits a comparatively steeper slope and lower device threshold, which are both desirable for mmLETFEL device activation. Characteristics of mmLETFEL test devices grown with base electrodes PolySi and TiW have been comparable, and this indicates that the deposition of these two materials have no significant effect on the mmLETFEL device performance.

SPICE modelling has been conducted on commercially available drivers from various fabrication houses based on the SPICE model parameters obtained from these manufacturers. Due to cost and technology accessibility, the 100V process DMOS device from Alcatel Mietec in Belgium has been selected for further investigation. Electrical characterisation and SPICE modelling have been performed on test dies (of the NDMOSHV model) obtained via EuroPractice. Comparison between the measured and simulated results shows a <10% error margin in the saturation region for the transistor output characteristics, and a <5% error margin for the transistor transfer characteristics.

This leads to circuit simulation using SPICE of the novel integrated mmLETFEL pixel - combining the developed mmLETFEL model and the optimised NDMOSHV model. By using previously characterised results of the mmLETFEL test devices to form a simple equivalent circuit, and the optunised SPICE parameters of the NDMOSHV model from Alcatel Mietec, the OEIC equivalent circuit has been developed and theoretically simulated for its performance.

Consequently, the processing route for an integrated mmLETFEL pixel is proposed, utilising the materials previously determined for the insulators and base electrodes. In addition, the results of the latest developments to the mmLETFEL technology from the aspects of fabrication, outcoupling efficiency, and overall performance, that are being investigated concurrently, have influenced the outcome of this research.

Item Type: Thesis
Creators: Theng, S.P.S.
Date: 2001
ISBN: 9781369325744
Rights: This copy of thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with the author and that no information derived from it may be published without the author’s prior written consent.
Divisions: Schools > School of Science and Technology
Record created by: Laura Ward
Date Added: 08 Jul 2021 09:02
Last Modified: 22 May 2024 14:32
URI: https://irep.ntu.ac.uk/id/eprint/43371

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