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Nader R.,University Paul Sabatier | Pezoldt J.,Institute of Micro and Nanotechnologies MacroNano
Diamond and Related Materials | Year: 2011

Optical measurements are used to investigate the crystalline quality and the stress in thin AlN layers; these thin films are grown on cubic silicon carbide layers which are in turn grown on silicon (111) substrates. Different Ge amounts were deposited at the silicon substrate in order to reduce the lattice parameters mismatch between Si and SiC grown layers. The residual stress of the hexagonal AlN layers is derived from the phonon frequency shifts of the E 1(TO) phonon mode. The crystalline quality of AlN films is investigated by considering the intensity of E1(TO) mode of the 2H-AlN and its full width of the half maximum (FWHM). Ge deposition at low temperature 325°C, before the carbonization process leads to an improved crystalline quality and a reduced residual stress in the AlN/SiC/Si heterostructures. The best crystalline quality and the lowest stress value are found in the case where 1ML Ge amount was predeposited. The E1(TO) mode, phonon frequency shifts-down by 3 cm- 1/GPa with respect to an unstrained layer. The obtained values for the phonon deformation are in reasonable agreement with theoretical calculations. © 2011 Elsevier B.V. All rights reserved. Source


Witte H.,Institute of Micro and Nanotechnologies MacroNano | Stubenrauch M.,TU Ilmenau | Frober U.,Institute of Micro and Nanotechnologies MacroNano | Fischer R.,Institute of Micro and Nanotechnologies MacroNano | And 2 more authors.
Engineering in Life Sciences | Year: 2011

A life support system for the cultivation of adherent 2-D and scaffold-based 3-D cell cultures in a microfluidic device, a Bio-Micro-Electro-Mechanical System (BioMEMS) is presented. The miniaturization level and system set-up allow incubator-independent operation modes and long-term experiments with real-time microscope observation. A dedicated seeding procedure for adherent cells into the microstructures is one key issue of the BioMEMS developed. Several seeding methods for the cells were evaluated. Biocompatibility of all materials, surfaces and methods could be demonstrated. First experiments with several cell types show the feasibility of the approach employing standard laboratory protocols. At present, the modular design and set-up offer a broad application spectrum as well as its future extension to e.g. cultivation of other cell types, coupled cultivation chambers and the implementation of other manipulation or analysis components. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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