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Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references.

Thesis (M.S.) in Electrical Engineering--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 110-113).

published_or_final_version / abstract / toc / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--Lehigh University, 1997. / Includes vita. Includes bibliographical references.

Thesis (Ph. D.)--Oregon Graduate Center, 1988.

Graduation date: 2002

The objective of the research presented in this thesis is to develop, implement, and demonstrate the utility of an n-sheet, state-space alternating-current thin-film electroluminescent (ACTFEL) device model. In this model, the phosphor layer is discretized into n + 1 layers, with band-to-band impact ionization, space charge creation/ annihilation, and luminescent impurity excitation/do-excitation occurring only at n sheets between the n + 1 layers. The state-space technique is a structured approach in which the ACTFEL device physics implementation is separated from the ACTFEL measurement circuit electrical response, resulting in a set of coupled, first-order differential equations which are numerically evaluated. The device physics implementation begins with electron injection from phosphor/insulator interfaces and band-to-band impact ionization. Phosphor layer space charge generation via band-to-band impact ionization and subsequent hole trapping, trap-to-band impact ionization, and shallow donor trap emission are then added to the model. Finally, impact excitation and radiative relaxation are added to the model to account for ACTFEL device optical properties. The utility of the n-sheet, state-space ACTFEL device model is demonstrated in simulations which verify hypotheses regarding ACTFEL device measured characteristics. The role of phosphor layer hole trapping and subsequent thermionic emission in SrS:Cu ACTFEL device EL thermal quenching is verified via simulation. Leaky ACTFEL device insulators are shown to produce high luminance but low efficiency. A novel space charge estimation technique using a single transferred charge curve is presented and verified via simulation. Hole trapping and trap-to-band impact ionization are shown to produce realistic overshoot in C-V curves, and each results in a different phosphor layer space charge distribution. DC coupling of the sense capacitor used in the measurement circuit to the applied voltage source is required for the generation of ACTFEL device electrical offset, as verified by simulation. Shallow donors are identified as a probable SrS:Ce ACTFEL device leakage charge mechanism. A field-independent emission rate time constant model is shown to yield realistic ZnS:Mn ACTFEL device leakage charge trends. / Graduation date: 2001

The goal of this thesis study is to develop an activated reactive evaporation (ARE) system and to demonstrate its utility by fabricating-alternating current thin-film electroluminescent (ACTFEL) oxide phosphor devices. ARE entails evaporation in an activated gas. The main ARE system components are three thermal evaporation sources, a microwave power supply, an electron cyclotron resonance plasma (ECR) source, a substrate heater/controller, a film thickness monitor, and a leak valve for gas flow control. Ga���0���:Eu ACTFEL devices are fabricated using the ARE system. The maximum Ga���O: deposition rate is approximately 2 nm/s. As-deposited films are transparent, insulating, and amorphous with an index of refraction of 1.68 and an optical bandgap of 4.25-4.9 eV. Ga���O��� films are typically amorphous until annealed above 1000��C in a furnace or by rapid thermal annealing. However, when hydrothermal annealing is employed, Ga���O��� films crystalize at temperatures as low as 450��C. Electrical and optical characterization indicates that the Ga���O���:Eu ACTFEL devices have very little charge transfer and emit very dim, orange-red electroluminescence with an emission peak of about 615 nm. / Graduation date: 2001

Graduation date: 1993