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Doctoral Thesis
DOI
10.11606/T.43.1995.tde-12072013-154933
Document
Author
Full name
Elvira Leticia Zeballos Velasquez
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 1995
Supervisor
Committee
Fantini, Marcia Carvalho de Abreu (President)
Alvarez, Fernando
Fazzio, Adalberto
Missell, Frank Patrick
Torriani, Iris C Linares de
Title in Portuguese
Caracterização de super-redes semicondutoras amorfas por difração de raios x.
Keywords in Portuguese
Difração de raios-x
Matéria condensada
semicondutores
Semicondutores amorfos.
Super-redes
Abstract in Portuguese
Neste trabalho foram investigados dois sistemas de multicamadas de semicondutores amorfos, a-SI:h/SI IND.1-XC IND.X:h e a-SI:h/a-GE:h, crescidos pela técnica de plasma enhanced chemical vapor deposition (PECVD). A difração de raios x a baixo angulo (SAXRD) foi a técnica utilizada para estudo das propriedades estruturais destas super-redes. Os objetivos deste trabalho foram: a) determinar as propriedades estruturais destes sistemas, no que tange a periodicidade da super-rede, uniformidade em espessura e tipo de interface; b) desenvolver modelos teóricos de simulação das intensidades difratadas; e c) avaliar o processo de difusão e cristalização dos componentes das multicamadas, através de tratamentos térmicos. As multicamadas de a-SI:h/a-SI IND.1-XC IND.X:h foram crescidas variando-se dois parâmetros de deposição: a concentração de metano na mistura gasosa e o tempo de plasma etching de hidrogênio entre deposições consecutivas. A combinação dos resultados de espectroscopia de eletrons auger (aes) e saxrd permitiram avaliar a espessura das interfaces. Interfaces mais abruptas foram obtidas em sistemas crescidos sobre uma camada buffer, tempos de plasma etching de hidrogênio de, pelo menos, 2min, e camadas de a-SI IND.1-XC IND.X:H crescidas com mais alta concentração de CH IND.4 na mistura gasosa e em condições de baixo fluxo de silano.
Title in English
Characterization of amorphous semiconductive super-networks by x-ray diffraction.
Keywords in English
Amorphous Semiconductors.
Condensed matter
semiconductor
Super-networks
x-ray diffraction
Abstract in English
In this work, two types of amorphous semiconductor multilayers were investigated, a-SI:h/SI IND.1-XC IND.X:h and a-SI:h/a-GE:h, deposited by the Plasma Enhanced Chemical Vapor Deposition (PECVD) method. The Small Angle X-Ray Diffraction (SAXRD) technique was used to study the structural properties of these super-lattices. The aim of this work was: a) to determine the structural properties of these systems, including the periodicity, thickness uniformity and interface sharpness; b) to develop theoretical models to simulate the diffracted intensities; and c) to evaluate the diffusion and crystallization processes of the multilayer components, by means of heat treatments. The a-SI:h/a-SI IND.1-XC IND.X multilayers were deposited, varying two growth parameters: the methane concentration in the gaseous mixture and the intermediate plasma etching time between consecutive depositions. The Auger Electron Spectroscopy (AES) and SAXRD results were combined to evaluate the interface thickness. The sharpest interfaces were obtained on samples deposited on top of a buffer layer, plasma etching times of at least 2 min. and a-SI IND.1-XC IND.X:H layers deposited with a higher CH IND.4. concentration in the gaseous mixture and in conditions of low silane flow.
 
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Publishing Date
2013-07-12
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • VELASQUEZ, E. L. Z., et al. Effect of plasma etching, carbon concentration, and buffer layer on the properties of a-Si:H/a-Si1−xCx:H multilayers [doi:10.1063/1.355836]. Journal of Applied Physics [online], 1994, vol. 75, nº 1, p. 543.
  • VELASQUEZ, E. L. Z., and FANTINI, M. C. A. Small angle X-ray diffraction study of a-Si:H/a-Ge:H multilayers: reflectivity modeling and thermal stability [doi:10.1016/s0022-3093(96)00561-3]. Journal of Non-Crystalline Solids [online], 1997, vol. 209, p. 175-187.
  • VELÁSQUEZ, E. L. Z., FANTINI, M. C. A., and MONCADA, H. L. Reflectivity modeling of Si-based amorphous superlattices. Superlattices and Microstructures, 2000, vol. 28, nº 3, p. 207-215.
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