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Fabrication of 3D diamond membranes for microfluidic systems
Varga, Marián ; Babchenko, Oleg ; Bauerová, Pavla ; Hruška, Karel ; Jurka, Vlastimil ; Kromka, Alexander ; Rezek, Bohuslav
Perfusion of cell medium, especially in microfluidic devices, can provide in-vivo-like conditions for cell cultures. The most recent demand on such systems is to include electronically active artificial cell support for in-situ monitoring. Diamond thin films exhibit advantageous combination of physical, mechanical, chemical, biocompatible and electronic properties for this purpose. In this work we explore two strategies for fabrication of self-standing three-dimensional nanocrystalline diamond membrane for implementation in microfluidic invivo like experiments: i) nucleation and chemical vapour deposition (CVD) growth of diamond on porous 3D carbon foam (with 80 pores per inch) and ii) selective diamond growth predefined by photolithographic processing using copper grid mask. The morphology and material quality of the fabricated membranes are characterized by scanning electron microscopy and Raman spectroscopy.
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Nanodiamond seeding of rough substrates
Vlčková, M. ; Stefanovič, M. ; Petrák, V. ; Fendrych, František ; Taylor, Andrew ; Fekete, Ladislav ; Nesládek, M.
Efficient growth of nanocrystalline diamond (NCD) requires nucleation enhancement before chemical vapour deposition step. Nanodiamond (ND) seeding is a commonly used technique that yields high nucleation densities. This technique is well established for conventional planar substrates with low surface roughness. However, many engineering application requires NCD grow on rough and/or non-planar substrates. In this work, we investigate quality of nanodiamond seeding on silicon substrates of high surface roughness (RMS roughness <1 mm). Seeded substrates and deposited diamond films were analysed by atomic force microscopy (AFM), scanning electron microscopy (SEM) and Raman spectroscopy. We discuss influence of nanodiamond particles in seeding solution and seeding technique on nucleation density and quality of deposited NCD film.
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Perspectives in diamond thin film technology
Kromka, Alexander
Synthetic diamond thin films are routinely grown over world not only for basic research but also for industrial uses. At the Institute of Physics (IoP), diamond thin films are grown since 2002. The first installed deposition system is base on microwave plasma enhanced chemical vapor deposition (CVD) in hydrogen reach gas mixture (<2% methane diluted in hydrogen). This system is well suitable for fast growth of high quality diamond films up to 5 cm in diameter. The main advance of the system is cavity like resonator which allows running stable CVD process for several days at relatively high pressures (>200 mbar).
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Photonic structures and their preparation
Varga, Marián ; Ondič, Lukáš ; Hruška, Karel ; Potměšil, Jiří ; Libertínová, Jitka ; Kromka, Alexander ; Remeš, Zdeněk
Photonic crystals are periodically structured electromagnetic media, generally possessing photonic band gaps: ranges of frequency in which light cannot propagate through the structure. This periodicity, which length scale is proportional to the wavelength of light in the band gap, is the electromagnetic analogue of a crystalline atomic lattice, where the latter acts on the electron wavefunction to produce the familiar band gaps of semiconductors, and so on, in solid-state physics. Several examples of organisms and structures possessing photonic crystals and iridescence are visible all around us (Morpho didius, Pavo cristatus, Chrysochroa vittata, Chrysina resplendens, …).
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Study of nucleation and growth of diamond thin films
Ižák, Tibor ; Babchenko, Oleg ; Varga, Marián ; Potocký, Štěpán ; Marton, M. ; Vojs, M. ; Domonkos, Mária ; Kromka, Alexander
This study deals with the nucleation and growth of CVD diamond films on Si substrates. In nucleation part two different nucleation methods were studied: (i) the bias enhanced nucleation (BEN) and (ii) ultrasonic seeding. In the case of BEN, (i) the nucleation time and (ii) the influence of bias voltage were studied. For ultrasonic seeding the effect of different solutions of ultradisperzed detonation nanodiamond (UDD) powder with metal particles on the nucleation efficiency and growth process was investigated (i.e. diamond powder, nanosized Ni, microsized Co and Y metal powders).
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Intrinsic and boron-doped diamond microstructured for electrochemical batteries
Kromka, Alexander ; Babchenko, Oleg ; Rezek, Bohuslav ; Ižák, Tibor ; Libertínová, Jitka ; Hruška, Karel ; Nyholm, L. ; de Oliviera Jorge, E.
Diamond - widest electrochemical window, excellentfor covalent binding of molecules, effective csarge transfer.
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