Utilize este identificador para referenciar este registo:
https://hdl.handle.net/1822/49067
Título: | SiGe layer thickness effect on the structural and optical properties of well-organized SiGe/SiO2 multilayers |
Autor(es): | Vieira, E. M. F. Toudert, J. Rolo, Anabela G. Parisini, A. Leitão, J. P. Correia, M. R. Franco, N. Alves, E. Chahboun, Adil Martín-Sánchez, J. Serna, R. Gomes, M. J. M. |
Palavras-chave: | SiGe multilayer structure RF magnetron sputtering TEM photoluminescence spectroscopic ellipsometry Raman spectroscopy nanocrystals SiGe nanocrystals |
Data: | 24-Jul-2017 |
Editora: | IOP Publishing |
Revista: | Nanotechnology |
Resumo(s): | In this work, we report on the production of regular (SiGe/SiO2)20 multilayer structures by conventional RF-magnetron sputtering, at 350 °C. Transmission electron microscopy, scanning transmission electron microscopy, raman spectroscopy, and x-ray reflectometry measurements revealed that annealing at a temperature of 1000 °C leads to the formation of SiGe nanocrystals between SiO2 thin layers with good multilayer stability. Reducing the nominal SiGe layer thickness (t SiGe) from 3.5-2 nm results in a transition from continuous SiGe crystalline layer (t SiGe ∼ 3.5 nm) to layers consisting of isolated nanocrystals (t SiGe ∼ 2 nm). Namely, in the latter case, the presence of SiGe nanocrystals ∼3-8 nm in size, is observed. Spectroscopic ellipsometry was applied to determine the evolution of the onset in the effective optical absorption, as well as the dielectric function, in SiGe multilayers as a function of the SiGe thickness. A clear blue-shift in the optical absorption is observed for t SiGe ∼ 2 nm multilayer, as a consequence of the presence of isolated nanocrystals. Furthermore, the observed near infrared values of n = 2.8 and k = 1.5 are lower than those of bulk SiGe compounds, suggesting the presence of electronic confinement effects in the nanocrystals. The low temperature (70 K) photoluminescence measurements performed on annealed SiGe/SiO2 nanostructures show an emission band located between 0.7-0.9 eV associated with the development of interface states between the formed nanocrystals and surrounding amorphous matrix. |
Tipo: | Artigo |
URI: | https://hdl.handle.net/1822/49067 |
DOI: | 10.1088/1361-6528/aa7a50 |
ISSN: | 0957-4484 |
e-ISSN: | 1361-6528 |
Versão da editora: | http://iopscience.iop.org/article/10.1088/1361-6528/aa7a50 |
Arbitragem científica: | yes |
Acesso: | Acesso restrito UMinho |
Aparece nas coleções: | CDF - CEP - Artigos/Papers (with refereeing) |
Ficheiros deste registo:
Ficheiro | Descrição | Tamanho | Formato | |
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SiGe layer thickness effect on ... well-organized SiGe_SiO2 multilayers.pdf Acesso restrito! | SiGe paper 2017 | 3,6 MB | Adobe PDF | Ver/Abrir |