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Mass production of hydrogenated ZnO nanorods
Chang, Yu-Ying ; Remeš, Zdeněk ; Míčová, J.
We have developed an inexpensive and efficient technology of hydrothermal growth of ZnO nanorods from zinc nitrate hexahydrate (Zn(NO3)2·6H2O), as a precursor and hexamethylenetetramine (HMTA) (C6H12N4), as a surfactant followed by plasma hydrogenation in a novel inductively coupled plasma (ICP) quartz reactor and equipped with the rotary sample holder to stir powder during plasma treatment. We have optimized the photoluminescence spectroscopy for measuring optical scattering samples with the high sensitivity, precise sample positioning and very low influence of the scattered excitation light. Here we present the latest results on the enhancement of the UV photoluminescence of the ZnO nanorods after plasma hydrogenation. The exciton-related photoluminescence has been significantly enhanced whereas the deep defect related yellow photoluminescence has been significantly decreased.\n
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The photoluminescence and optical absorptance of plasma hydrogenated nanocrystalline ZnO thin films
Remeš, Zdeněk ; Chang, Yu-Ying ; Stuchlík, Jiří ; Mičová, J.
We have developed the technology of the deposition of the nominally undoped ZnO nanocrystalline thin films by DC reactive magnetron sputtering of Zn target in the gas mixture of argon and oxygen plasma. We have optimized the photoluminescence spectroscopy for measuring optically scattering thin layers with the high sensitivity, precise sample positioning and very low influence of the scattered excitation light. Here we present the latest results on the enhancement of the photoluminescence of the nanocrystalline ZnO thin films after plasma hydrogenation. The photoluminescence in near UV region has been enhanced whereas the deep defect related photoluminescence has been significantly decreased. We found good room temperature stability of the plasma hydrogenated ZnO nanocrystals in air, but fast degradation at elevated temperature\n
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The hydrogen plasma doping of ZnO thin films and nanoparticles
Remeš, Zdeněk ; Neykova, Neda ; Potocký, Štěpán ; Chang, Yu-Ying ; Hsu, H.S.
The optical absorptance and photoluminescence studies has been applied on the hydrogen and oxygen plasma treated, nominally undoped ZnO thin films and aligned nanocolumns grown on the nucleated glass substrate by the hydrothermal process in an oil bath containing a flask with ZnO nutrient solution. The localized defect states at 2.3 eV below the optical absorption edge were detected by photothermal deflection spectroscopy (PDS) in a broad spectral range from near UV to near IR. The optical absorptance spectroscopy shows that hydrogen doping increases free electron concentration changing ZnO to be electrically conductive (hydrogen doping).\n
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Preparation of zinc oxide nanorods colloid from thin layers
Mičová, Júlia ; Remeš, Zdeněk ; Chang, Yu-Ying ; Neykova, Neda
The interest in ZnO (zinc oxide) nanoparticles is increasing due to low cost of their processing as well as the ability of fabricating ZnO nanostructures with controllable morphology such as size, shape and orientation. Our choice of method of the preparation of the nanostructured thin ZnO layers is the hydrothermal growth of ZnO nanorods on glass substrates coated by the nucleation layer deposited by the reactive magnetron sputtering. We have developed and optimized conditions of the thin layer growth with controllable dimensions of nanorods followed by the ultrasound peeling. The colloid of ZnO nanorods was characterized by measuring the size of particles using the dynamic light scattering (DLS) and the scanning electron microscopy (SEM). We found that the dynamic light scattering (DLS) can’t be directly used for size evaluation of ZnO nanorods due to their non- sperical shape. \n
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Hydrogen plasma treatment of ZnO thin films
Chang, Yu-Ying ; Neykova, Neda ; Stuchlík, Jiří ; Purkrt, Adam ; Remeš, Zdeněk
ZnO is an attractive wide band gap semiconductor with large exciton binding energy, high refractive index, high biocompatibility and diversety of nanostructure shapes which makes it suitable for many applications in the optoelectronic devices, optical sensors, and biosensors. We study the effect of hydrogen plasma treatment of the nominally undoped ZnO thin film deposited by DC reactive magnetron sputtering of Zn target in the gas mixture of argon and oxygen plasma. The SEM images show that the crystal size increases with film thickness. We confirm, that the electrical conductivity significantly increases after hydrogen plasma treatment by 4 orders of magnitude. Moreover, the increase of the infrared optical absorption, related to free carrier concentration, was detected below the optical absorption edge by the photothermal deflection spectroscopy.\n
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