The purpose of these experiments was to determine the degradation mechanisms of molybdenum based field emitter arrays to oxygen exposures and to improve the overall reliability. In addition, we also evaluated the emission current stability of gold-coated field emitter arrays to oxygen exposures. oxygen at 1x10-6 torr was introduced into the chamber through a leak valve for different lengths of time and duty cycles. To ensure identical oxygen exposure and experimental measurement conditions, tips on half the area of the FEA were fully coated with gold and the other half were left uncoated. The emission current from the gold coated half was found to degrade much less than that from the uncoated half, in the presence of oxygen. Also in the absence of oxygen, the emission current recovery for the gold-coated side was much quicker than that for the uncoated side.

Orientador: Marco Antonio Robert Alves / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-09T17:44:13Z (GMT). No. of bitstreams: 1 Tirolli_MarceloNogueira_M.pdf: 2758197 bytes, checksum: 08f6e633be3e083c0e72c41959dd296d (MD5) Previous issue date: 2007 / Resumo: Este trabalho tem como objetivo o estudo do comportamento elétrico de uma ponteira de emissão de campo, modelada na forma de um hemisfério sobre um poste, através de recursos computacionais (simulações). Escolhemos o software comercial Ansys, que utiliza o método dos elementos finitos nas análises dos fenômenos físicos para obtenção do campo elétrico na superfície da ponteira. Em seguida, foi desenvolvido também um programa computacional que realiza o cálculo da corrente de emissão baseado na teoria de emissão de campo de Fowler-Nordheim (F-N). Para calcular a corrente, o programa faz uso dos resultados das simulações do campo elétrico obtidos no software Ansys. Apresentamos também os resultados da influência que as dimensões como o raio de curvatura do hemisfério, a altura da ponteira e a distância entre anodo e catodo exercem sobre o comportamento do campo elétrico, da corrente de emissão e de outras grandezas físicas que envolvem emissão de campo / Abstract: This work aims to study the electrical behavior of a field emission tip, shaped in the form hemisphere on a post, through computational resources (simulations). We chose the Ansys commercial software that uses the finite element methods in the analyses of the physical phenomena to obtain the electric field in the surface of the tip. After that, a computational program was also developed to perform the calculation of emission current based on Fowler-Nordheim (F-N) field emission theory. To calculate the current, the program uses the results of the electric field simulations gotten in Ansys software. We also show the results of influences that dimensions such as the hemisphere curvature radius, the height of the tip and the distance between anode and cathode exert on the behavior of the electric field, emission current and other physical quantities that involve field emission / Mestrado / Eletrônica, Microeletrônica e Optoeletrônica / Mestre em Engenharia Elétrica

In this work, a new organic light-emitting device (OLED) structure is proposed that allows light-emission from a metal-free device region, thus reducing the hurdles towards an electrically pumped organic solid state laser (OSL). Our design concept employs a stepwise change from a highly conductive but opaque metal part to a highly transparent but less conductive intrinsic emission layer. Here, the high current densities are localized to an area of a few micrometer in square, which is in the range of the mode volume of the transverse mode of an organic vertical-cavity surface-emitting laser (VCSEL). Besides these experimental results, we present findings from simulations which further support the feasibility of our design concept. Using an equivalent circuit approach, representing the current ow in the device, we calculate the time-dependent length of the emission zone and give estimations for appropriate material parameters.