Filmes finos de compostos semicondutores: preparação de CdS e da junção Cu2-XSe/MEH-PPV

by Rabelo, Adriano César

Abstract (Summary)
In this work thin films of semiconductor compounds were prepared.Focus was on a recipe for preparation of cadmium sulphide onto copperselenide substrate. Copper selenide thin films dissolve when in contactwith the chemical bath for deposition cadmium sulphide. This drawbacktriggered an investigation for using milder chelating agents. A new bathcomposition was determined from chemical equilibrium analysis ofabout ten species supposedly present in the bath, mass balance andcharge balance. From the results, a thin film of. cadmium sulphide hasbeen prepared on glass substrate by chemical bath deposition usingsodium acetate, sodium hydroxide and thiourea. Absorption spectra ofthe film in the visible range was registered and compared with thespectra from others authors. The band gap of the film was estimatedfrom the spectra. The junction copper selenide and poly-2-methoxy-5-(2?-ethylhexyloxy)-phenylenevinilene was prepared and characterized.Copper selenide was prepared on copper by chemical bath depositionusing sodium selenosulphate. The polymeric film was prepared bycasting technique, in which the polymer is dissolved in tetrahidrofurane,dropped onto the substrate and let to dry. Ohmic contact was preparedusing graphite conductive glue. This glue was developed for thispurpose and is made up from graphite powder, epoxy andpolimercaptan dissolved in tetrahidrofurano. The electrical properties ofthe junction were determined from current-potential curves. By usingthe Fowler-Nordheim model, the energy barrier height was calculated.The results were compared with the literature results obtained with asimilar devices, namely ITO/MEH-PPV. The energy barrier height ofcopper selenide/MEH-PPV is about thirty times smaller than the energybarrier height of ITO/MEH-PPV. The conclusion is that copper selenideis a promising material for use in photoluminescent diodes.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Alexandre Marletta; Otavio Luiz Bottecchia; Leonardo Morais da Silva

School:Universidade Federal de Uberlândia

School Location:Brazil

Source Type:Master's Thesis

Keywords:quimica filmes finos


Date of Publication:07/31/2008

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