Estudo da fotocapacitância em dispositivos MIS orgânicos
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Data
2012-02-27
Autores
Sabino, Fernando Pereira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A eletrônica orgânica é muito atrativa para a fabricação de circuitos flexiveis e de grande área a partir de soluções em solventes orgânicos. Entretanto, dispositivos totalmente orgânicos devem incluir transitores, e estes ainda necessitam ser aprimorados para que possam ser comercializados, sendo que os principais desafios são aumentar a capacidade de chaveamento de corrente e melhorar a estabilidade. Estes fatores podem estar relacionados com as propriedades dos semicondutores orgânicos, como a distribuição das bandas de energia, mecanismo de transporte de cargas, mobilidade dos portadores, entre outros. Assim, as equações convencionais de semicondutores inorgânicos devem ser devidamente adaptadas para que possam ser aplicadas aos dispositivos orgânicos. Nesta dissertação estuda-se o capacitador metal-isolante-semicondutor (MIS), que é usualmente, caracterizado através de medidas de capacitância e perde dielétrica em função de freqüência e da voltagem. Representa-se a amostra por circuitos equivalentes para simular as curvas de capacitância e perda dielétrica em função da voltagem. Um circuito básico que serve como gabarito, onde os demais efeitos podem ser inclusos, é apresentado, e dentre esses efeitos são estudados a análise da camada de acumulação, estados interfaciais e a interação do MIS com a luz. Mostra-se que as curvas de capacitância e perda dialética simuladas reproduzem adequadamente o comportamento dos estados interfaciais gerando um pico nas curvas de perda dielétrica em função da voltagem, cuja posição e intensidade variam com a densidade de estados interfaciais, a probabilidade de captura e a frequencia. Também é estudada a geração de portadores devido a iluminação. Os efeitos da iluminação podem ser modelados incluindo um capacitar no...
The organic electronics is very attractive for manufacturing flexibe and large area circuits using solutions with organic with organic solvents. However, all-organic devices must include transistors, which need improvements in order to be commercialized, being the main challenges the increasing on the current switching capability and the improving on the stability. These factors may be related with the properties of organic semiconductors, such as the energy band distribution, charge transport mechanisms, mobility and others. Thus, the equations used to conventional inorganic semiconductors must be adapted for its application to the organic devices. In this dissertation the metal-insulator-semiconductor (MIS) capacitor is studied, which is usually characterized by capacitance and dielectric loss measurements as a function of frequency and voltage. The sample is represented by equivalent circuits in order to simulate the capacitance and the dielectric loss curves as a function of voltage. A basic circuit that serves as a template were other effects can be included is presented and, among these effects, the accumulation layer, the interfacial states and the light interaction with the MIS device are studied. It is shown that the curves simulated for capacitance and dielectric loss properly reproduce the interfacial states behavior, with a peak in the dielectric loss curves as a function of voltage, whose intensity and position change with the interfacial state density, capture probability and frequency. The carrier generation due to the illumination is also studied. The illumination effects can be modeled by the inclusion of a capacitor in the equivalant circuit, which capacitance depends on factors such as light intensity, generation rate and capture and recombination of carriers. It is also shows that the proposed... (Complete abstract click electronic access below)
The organic electronics is very attractive for manufacturing flexibe and large area circuits using solutions with organic with organic solvents. However, all-organic devices must include transistors, which need improvements in order to be commercialized, being the main challenges the increasing on the current switching capability and the improving on the stability. These factors may be related with the properties of organic semiconductors, such as the energy band distribution, charge transport mechanisms, mobility and others. Thus, the equations used to conventional inorganic semiconductors must be adapted for its application to the organic devices. In this dissertation the metal-insulator-semiconductor (MIS) capacitor is studied, which is usually characterized by capacitance and dielectric loss measurements as a function of frequency and voltage. The sample is represented by equivalent circuits in order to simulate the capacitance and the dielectric loss curves as a function of voltage. A basic circuit that serves as a template were other effects can be included is presented and, among these effects, the accumulation layer, the interfacial states and the light interaction with the MIS device are studied. It is shown that the curves simulated for capacitance and dielectric loss properly reproduce the interfacial states behavior, with a peak in the dielectric loss curves as a function of voltage, whose intensity and position change with the interfacial state density, capture probability and frequency. The carrier generation due to the illumination is also studied. The illumination effects can be modeled by the inclusion of a capacitor in the equivalant circuit, which capacitance depends on factors such as light intensity, generation rate and capture and recombination of carriers. It is also shows that the proposed... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Capacitador MIS orgânico, Fotocapacitância, MIS capacitors
Como citar
SABINO, Fernando Pereira. Estudo da fotocapacitância em dispositivos MIS orgânicos. 2012. 86 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências e Tecnologia, 2012.