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Doctoral Thesis
DOI
10.11606/T.43.2002.tde-13122013-121304
Document
Author
Full name
Sandro Martini
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2002
Supervisor
Committee
Quivy, Alain Andre (President)
Fantini, Marcia Carvalho de Abreu
Ferraz, Armando Corbani
Rodrigues, Wagner Nunes
Souza, Patrícia Lustoza de
Title in Portuguese
Estudo da segregação de Índio em camadas epitaxiais de In IND. X Ga IND. 1-X acrescidas sobre substratos de GaAs (001).
Keywords in Portuguese
Fotoluminescência
MBE
Poços quânticos
Segregação
Abstract in Portuguese
Neste trabalho, estudamos o crescimento epitaxial por feixe molecular assim como as propriedades ópticas e estruturais de camadas de InGaAs depositadas sobre substratos de GaAs(001) com diferentes ângulos e direções de corte. Um ênfase foi dada à investigação da segregação dos átomos de Índio que modifica consideravelmente o perfil de potencial das heteroestruturas e influencia as características dos dispositivos contendo este tipo de camadas. Um novo método experimental baseado em medidas de difração de elétrons de alta energia (RHEED) possibilitou a determinação in situ e em tempo real do coeficiente de segregação dos átomos de Índio e, conseqüentemente, do perfil de composição das camadas de InGaAs. Medidas de raios X e de fotoluminescência em baixa temperatura foram realizadas em amostras de poços quânticos de InGaAs e confirmaram, a posteriori, os resultados obtidos pela técnica RHEED. Foi também demonstrado que o uso de substratos desorientados podia reduzir levemente o efeito de segregação e melhorar as propriedades ópticas das camadas em baixa temperatura.
Title in English
Study of indium segregation in epitaxial layers of InxGa1-xAs added on GaAs substrates (001).
Keywords in English
MBE
Photoluminescence
Quantum wells
Segregation
Abstract in English
In this work, we investigated the molecular-beam-epitaxy growth as well as the optical and structural properties of InGaAs layers deposited on top of GaAs (001) substrates with different miscut angles and directions. We emphasized the investigation of the segregation of In atoms that considerably modifies the potential profile of the heterostructures and influences the characteristics of the devices based on this type of layers. A new experimental method involving the diffraction of high-energy electrons (RHEED) allowed the in-situ and real-time determination of the segregation coefficient of the In atoms and, consequently, of the compositional profile of the InGaAs layers. X-rays and low-temperature photoluminescence measurements were carried out InGaAs quantum wells and confirmed, a posterior, the results obtained by the RHEED method. It was also demonstrated that the use of vicinal substrates slight reduces the segregation effect and improves the optical properties of the layers at low temperature.
 
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Publishing Date
2014-02-20
 
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