Diodo planar orgânico Schottky: construção e caracterização

• Ano de defesa: 2014
• Autor(a) principal: Paquola, Alexandre Guidio [UNESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Semicondutores; Diodos semicondutores; Schottky, Diodos de barreira de; Eletrodos; Diodos
• Link de acesso: http://hdl.handle.net/11449/123745; http://www.athena.biblioteca.unesp.br/exlibris/bd/cathedra/15-05-2014/000829903.pdf

Usually organic diodes are made with a semiconducting polymeric layer placed between two electrodes in a sandwich-like architecture. The fabrication process involves mainly two steps: a) film formation over a metallic substrate (bottom electrode) and b), metallic electrode deposition by thermal evaporation over the top surface. The main problem with this procedure is that the semiconductor film top surface becomes rough if compared with the bottom surface, which remains in contact with the substrate. Additionally the thermal evaporation of electrodes promotes diffusion of metal atoms into the semiconducting layer, making this interface not well defined. To avoid surface roughness and metal diffusion was developed, in this work, a bimetal (Au and Al) finger structure over which the semiconductor material was deposited. Undoped poly-o-methoxyaniline was deposited over the finger structure by drop casting and the doping was promoted by exposing the electrode-free surface to HCl acid (0.1 M). The devices current-voltage characteristic was monitored for different acid exposure time using a Keithley 2410 source/meter unity. Was verified that the diode characteristic curve shape is highly depend on the doping time, starting form a linear behavior up to a high quality diode curve. For acid exposure times higher than 250 s the diode characteristic curve starts to decay, pointing that acid diffusion was reached the finger electrode, causing electrode damaged. The lower diode ideality factor and turn-on voltage was  = 8 and VOP = 0.900  0.004 V, respectively. These values indicate that the minimum devices volume resistance was reached. Employing optimized exposure times was possible to design diodes with rectification ratio at about 25. Diode characterization in different temperatures indicates that the operation occurs typically by Schottky process