Estudo das estruturas Fe:GaAs e Fe:Cs:GaAs por espectroscopia de fotoelétrons excitados por raios-X

• Ano de defesa: 2005
• Autor(a) principal: Lauro Chieza de Carvalho
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: espectroscopia; GaAs; Espectroscopia fotoeletrônica; Filmes finos de ferro; Espectroscopia de fotoelétrons excitados por Raios X XPS; Arseneto de gálio
• Link de acesso: http://hdl.handle.net/1843/ESCZ-6KZNPJ

We used X-ray Photoelectron Spectroscopy to study the growth of iron on GaAs(100) mediated by Cesium. All GaAs substrates were Si 5 x 1017 cm-3 n-doped layers prepared by Molecular Beam Epitaxy. Iron was deposited by e-beam evaporation, and the Cesium source was a SAES Getters commercial dispenser. Three samples were prepared distingued by the Cesium coverages: zero, sub-monolayer (10 seconds Cs evaporation) and approximately 1 monolayer (120 seconds Cs evaporation). All depositions were done at room temperature. Our results for the sample without Cesium agree completely with the previous behavior already reported in the literature. A 8 Å Fe thick reacted layer is formed by deposition of iron on GaAs, and As segregates to the surface of the iron film. For the case of Cs containing samples the inversion reaction, which happens in the iron on GaAs case, is inhibited, and As no more segregate to the surface of film. However Cs does not avoid the formation of a reacted layer. The 10 seconds Cs sample presents a 16 Å Fe thick reacted layer, but none As, Ga or Cs segregated to the iron film surface. The 120 seconds Cs sample brings to a 32 Å Fe thick reacted layer, but almost all the Cs segregates to the iron growth front.