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Doctoral Thesis
DOI
10.11606/T.43.2001.tde-09122013-104429
Document
Author
Full name
José Rafael León Fernández
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2001
Supervisor
Committee
Chitta, Valmir Antonio (President)
Bindilatti, Valdir
Degani, Marcos Henrique
Galzerani, José Claudio
Pereyra, Ines
Title in Portuguese
Propriedades elétricas e vibracionais de nitretos cúbicos do grupo III
Keywords in Portuguese
Efeito hall
Nitretos cúbicos
Raman
Transporte
Abstract in Portuguese
Esta tese está dirigida ao estudo das propriedades elétricas e ópticas das camadas cúbicas de InN, GaN (intrínseco), GaN:Si (tipo-p), GaN:Si (tipo-n) e AlGaN. Por meio da técnica de efeito Hall e utilizando a configuração de Van der Pauw foram obtidas as curvas de resistividade, concentração e mobilidade em função da temperatura das camadas e através destas curvas é determinada a energia de ativação dos aceitadores e doadores. Também através das mesmas curvas são estudados os principais mecanismos que predominam no espalhamento dos portadores. Em alguns casos um comportamento anômalo foi observado (curvas de concentração e mobilidade do InN e GaN:Si (tipo-p)) e os resultados foram corrigidos utilizando-se o modelo de duas camadas e/ou modelo de duas bandas. Para o material c-InN medimos sua resistividade, concentração e mobilidade na região de baixas temperaturas para investigar um possível caráter supercondutor da amostra. Abordaremos também nesta tese o estudo teórico e experimental sobre a transição metal-semicondutor nos nitretos. Para o estudo das propriedades ópticas das camadas foi utilizada a técnica de caracterização de Raman. Por meio desta técnica e utilizando a configuração de retro espalhamento foram caracterizadas as camadas cúbicas de GaN (intrínseco), GaN:Si (tipo-p), GaN:Si (tipo-n) e AlGaN. Dos espectros, foram obtidas as posições dos picos pertencentes aos fônons transversal-ópticos (TO) e longitudinal-ópticos (LO). Verificou-se o caráter cúbico das camadas e estudou-se a origem da banda que aparece entre as posições dos modos TO e LO do material.
Title in English
Vibrational and electrical properties of cubic group III nitrides
Keywords in English
Cubic nitrides
Hall effect
Raman
Transport
Abstract in English
The thesis is devoted to the study of electrical and optical properties of cubic InN, GaN (undoped), GaN:Si (type-p), GaN:Si (type-n) and AlGaN epitaxial films. For the study of the electrical properties were measured the resistivity, concentration and mobility curves as a function of the temperature by means of Hall effect and Van der Pauw configuration technique. From these curves were obtained the activation energy of donor and acceptors levels and were studied the main dominant mechanisms for the electron scattering. In some cases an anomalous behavior of the curves was observed and was corrected using the two layer model. For the study of the superconductivity character of the cubic InN sample was measured its resistivity, concentration and mobility in the low temperature region. The thesis is also devoted to the theoretical and experimental studies of the metal-non-metal transitions in the nitrites.The optical studies of the GaN (undoped), GaN:Si (type-p), GaN:Si (type-n) and AlGaN films were done by means of Raman characterization according to a backscattering configuration. From the spectra were obtained the position of the TO and LO phonon peaks, was verified the cubic character of the films and was studied the behavior of the band found between the TO and LO phonon peaks.
 
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Publishing Date
2014-02-18
 
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