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Habilitation Thesis
DOI
10.11606/T.43.2014.tde-12112014-150058
Document
Author
Full name
Armando Corbani Ferraz
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1987
Committee
Ferreira, Luiz Guimaraes (President)
Baumvol, Israel Jacob Rabin
Chaves, Alaor Silverio
Oliveira, Mario Jose de
Zuffo, Joao Antonio
Title in Portuguese
ESTRUTURA ELETRONICA DE SUPERFICIES E SUPER-REDES DE SEMICONDUTORES
Keywords in Portuguese
ESTRUTURA ELETRONICA
SEMICONDUTORES
SUPERFICIES
Abstract in Portuguese
Usando o método de pseudopotencial autoconsistente, com energia total e forças de Hellmann-Feynman, no esquema de densidade local, as geometrias de equilíbrio das superfícies GaAs ( 110) e ZnSe (110) são determinadas, e as estruturas de faixas de energia das super-redes (GaAs)n(A~As)n e (GaAs)n(ZnSe)n são estudadas. Os resultados sugerem que as superfícies se reconstroem com ângulos de rotação de ~ 31° para o GaAs ( 11 O) e de ~ 25° para o ZnSe ( 1 10), e os deslocamentos laterais são de 0.53, 0.33, 0.39 e o 0.14 A para os átomos de Ga, As, Zn e Se, respectivamente. Os estados de energia de superfície calculados para as geometrias de equilíbrio, estão em boa concordância com os dados experimentais de fotoemissão. Nos sistemas de super-redes, a recente observação na variação do gap nas estruturas (GaAs)n(A~As)n é explicada, e uma previsão é feita para as camadas ultra-finas do (GaAs)n(ZnSe)n. Investigamos também as diferenças entre as propriedades eletrônicas de (GaAs) 1 (A~As) 1 e da liga A~ 0 . 5 Ga 0 . 5 As. Finalmente, a variação do gap no sistema (GaAs)n(A~As)n, é comparada e contrastada com aquela no ( GaAs)n ( ZnSe) n
Title in English
ELECTRONIC STRUCTURE OF SURFACES AND SUPER GOALKEEPER OF SEMICONDUCTORS
Keywords in English
ELECTRONIC STRUCTURE
SEMICONDUCTORS
SURFACES
Abstract in English
Using the self-consistent pseudopotential method with total energy and Hellmann-Feynman forces, within the local density approximation, the equilibrium surface geometries of GaAs ( 110) and ZnSe ( 110) are determined, and the electronic band structure of (GaAs)n(A~As)n and (GaAs)n(ZnSe)n superlattices are studied. The results suggest that the surfaces reconstructs with a top layer tilt angle of ::: 31° for GaAs ( 110), ::: 25° for ZnSe o (110), and lateral displacements are 0.53, 0.33, 0.39 and 0.14 A for Ga, As, Zn and Se, respectively. Calculated surface state energies for the equilibrium geometry are in good agreement with photoemission data. In the systems of superlattices, the recent observation on the variation of the band gap in (GaAs)n(A~As)n is explained, and a forecast to the ultra-thin (GaAs)n(ZnSe)n is dane. The diferences between the electronic properties of the ( GaAs) 1 ( A~As) 1 and the alloy A~ 0 . 5Ga 0 . 5 As are investigated. Finally, the variation of the band gap in (GaAs)n(ZnSe)n is compared and contrasted with that in (GaAs)n(A~As)n
 
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Publishing Date
2014-11-14
 
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