The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Ji Hoon Choi - One of the best experts on this subject based on the ideXlab platform.
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SiC Nanowires : from growth to related devices
2013Co-Authors: Ji Hoon ChoiAbstract:Low dimensional semiconductor nanostructures, such as nanowires (NWs), have become the focus of intensive research for exploring new emergent phenomena at the nanoscale and probing their possible use in future electronics. Among these semiconductor NWs, Silicon Carbide (SiC) has very unique properties, such as wide bandgap, excellent thermal conductivity, chemical and physical stability, high electron mobility and biocompatibility. These factors makes SiC a long standing candidate material to replace silicon in specific electronic device applications operating in extreme conditions or/and harsh environments. SiC nanostructures have been studied extensively and intensively over the last decade not only for their fabrication and characterization, but also for their diverse applications. I have outlined the growth of SiC nanostructures based on different growth methods, a noteworthy feature of their characteristic properties and potential applications in the chapter one. As-grown SiC NWs fabricated by bottom-up method present a high density of structural defects, such as stacking faults. This kind of defect is one of the factors which lead to poor electrical performance (such as weak gate effect and low mobility) of the related devices. Therefore, it is required to develop a high quality of SiC nanostructures with low density of the structural defects using an alternative method, such as top-down process. Main objectives of this thesis are divided into three main parts. The first part of the thesis (Chapter two), we present the simulation results of the electrical transport and thermoelectric properties of SiC NWs. I have investigated the thermoelectric enhancement by studying the complex interplay of the size of NWs, temperature and surface roughness. Our simulation results show that the ZT of C terminated SiC NW (2.05×2.05 nm2) reaches a maximum value of 1.04 at 600K. The second part of the thesis (Chapter there) is devoted to the fabrication of high quality SiC nanostructures with controlled doping level. I have developed a top-down fabrication technique for high quality nanometer scale SiC nanopillars (NPs) using inductively coupled plasma etching. The etching behavior of SiC NPs has also been studied depending on polytypes and crystallographic orientations. Under the optimal etching conditions using a large circular Mask Pattern with 370 nm diameter, the obtained 4H-SiC nanopillars exhibit high anisotropy features (6.4) with a large etch depth (>7μm). A hexagonal, rhombus and triangle based pillar structures have been obtained using α-SiC (0001), 3C-SiC (001) and 3C-SiC (111) substrates, respectively. The last part of the thesis (Chapter four) is dedicated to the design and the electrical characterization of SiC nanodevices. To investigate the electrical properties of SiC nanostructures, two different kinds of SiC nanoFETs (SiC NWFET and SiC NPFET) have been fabricated by using SiC NWs and SiC NPs prepared via bottom-up method and top-down methods, respectively. In case of SiC NWFET, low resistivity ohmic contacts (378 kΩ) have been obtained after the annealing at 650 °C. Ni silicide intrusion into the SiC NW channel has been observed the annealing at 700 °C. This temperature is compared to one of other group IV materials. In case of SiC NPFET, two different types of NPFET (3C-SiC (001) and 4H-SiC (0001)) have been fabricated using our SiC nanopillars, obtained by top-down approach. The estimated values of the field-effect carrier mobility are 232.7 cm2⋅V-1s-1 for 3C-SiC (001) NPFET (#2) and 53.6 cm2⋅V-1s-1 for 4H-SiC (0001) NPFET, which is higher than the best values reported in the literature (15.9 cm2⋅V-1s-1).
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fabrication of sic nanopillars by inductively coupled sf6 o2 plasma etching
Journal of Physics D, 2012Co-Authors: Ji Hoon Choi, Laurence Laturomain, Edwige Bano, F Dhalluin, T Chevolleau, T BaronAbstract:In this paper, we demonstrate a top-down fabrication technique for nanometre scale silicon carbide (SiC) pillars using inductively coupled plasma etching. A set of experiments in SF6-based plasma was carried out in order to realize high aspect ratio SiC nanopillars. The etched SiC nanopillars using a small circular Mask Pattern (115 nm diameter) show high aspect ratio (7.4) with a height of 2.2 µm at an optimum bias voltage (300 V) and pressure (6 mTorr). Under the optimal etching conditions using a large circular Mask Pattern with 370 nm diameter, the obtained SiC nanopillars exhibit high anisotropy features (6.4) with a large etch depth (>7 µm). The etch characteristic of the SiC nanopillars under these conditions shows a high etch rate (550 nm min−1) and a high selectivity (over 60 for Ni). We also studied the etch profile of the SiC nanopillars and Mask evolution over the etching time. As the Mask Pattern size shrinks in nanoscale, vertical and lateral Mask erosion plays a crucial role in the etch profile of the SiC nanopillars. Long etching process makes the pillars appear with a hexagonal shape, coming from the crystallographic structure of α-SiC. It is found that the feature of pillars depends not only on the etching process parameters, but also on the crystallographic structure of the SiC phase.
A Ougazzaden - One of the best experts on this subject based on the ideXlab platform.
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Mask Pattern interference in algainas selective area metal organic vapor phase epitaxy experimental and modeling analysis
Journal of Applied Physics, 2008Co-Authors: Nicolas Dupuis, J Decobert, Pierreyves Lagree, N Lagay, F Poingt, C Kazmierski, Abderrahim Ramdane, A OugazzadenAbstract:We studied selective area growth modeling and characterization of the AlGaInAs material system. We used a three-dimensional vapor phase diffusion model to extract the effective diffusion lengths of Al, Ga, and In species from measured thickness profiles of the three binaries AlAs, GaAs, and InP. Our growth conditions yield to 50, 85, and 10 μm for Al, Ga, and In, respectively. Based on these values, we achieved a precise prediction of AlGaInAs thickness, composition, band gap, and biaxial strain variations in different selective area growth conditions. Particular attention was paid to the influence of neighboring cells in the case of high Mask density. This configuration occurs in practical component Mask layout. High Mask density leads to interferences between Masked cells and enhances the effect of the long diffusion length of aluminum and gallium species. Then, the biaxial strain is tensile shifted and the band gap is blue shifted in the vicinity of a Mask, compared to reference material features grown...
Nicolas Dupuis - One of the best experts on this subject based on the ideXlab platform.
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Mask Pattern interference in algainas selective area metal organic vapor phase epitaxy experimental and modeling analysis
Journal of Applied Physics, 2008Co-Authors: Nicolas Dupuis, J Decobert, Pierreyves Lagree, N Lagay, F Poingt, C Kazmierski, Abderrahim Ramdane, A OugazzadenAbstract:We studied selective area growth modeling and characterization of the AlGaInAs material system. We used a three-dimensional vapor phase diffusion model to extract the effective diffusion lengths of Al, Ga, and In species from measured thickness profiles of the three binaries AlAs, GaAs, and InP. Our growth conditions yield to 50, 85, and 10 μm for Al, Ga, and In, respectively. Based on these values, we achieved a precise prediction of AlGaInAs thickness, composition, band gap, and biaxial strain variations in different selective area growth conditions. Particular attention was paid to the influence of neighboring cells in the case of high Mask density. This configuration occurs in practical component Mask layout. High Mask density leads to interferences between Masked cells and enhances the effect of the long diffusion length of aluminum and gallium species. Then, the biaxial strain is tensile shifted and the band gap is blue shifted in the vicinity of a Mask, compared to reference material features grown...
G. K. Skinner - One of the best experts on this subject based on the ideXlab platform.
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Coding (and decoding) coded Mask telescopes
Experimental Astronomy, 1995Co-Authors: G. K. SkinnerAbstract:Many designs of Masks for coded aperture telescopes have been proposed and a number of different configurations for instruments considered. Their advantages and disadvantages and some of the considerations involved in designing an instrument and in choosing a Mask are reviewed. The methods of image reconstruction, which strongly influence the choice of design, are discussed and a way of quantifying the effectiveness of a Mask Pattern when used with a detector of finite resolution is presented.
T Baron - One of the best experts on this subject based on the ideXlab platform.
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fabrication of sic nanopillars by inductively coupled sf6 o2 plasma etching
Journal of Physics D, 2012Co-Authors: Ji Hoon Choi, Laurence Laturomain, Edwige Bano, F Dhalluin, T Chevolleau, T BaronAbstract:In this paper, we demonstrate a top-down fabrication technique for nanometre scale silicon carbide (SiC) pillars using inductively coupled plasma etching. A set of experiments in SF6-based plasma was carried out in order to realize high aspect ratio SiC nanopillars. The etched SiC nanopillars using a small circular Mask Pattern (115 nm diameter) show high aspect ratio (7.4) with a height of 2.2 µm at an optimum bias voltage (300 V) and pressure (6 mTorr). Under the optimal etching conditions using a large circular Mask Pattern with 370 nm diameter, the obtained SiC nanopillars exhibit high anisotropy features (6.4) with a large etch depth (>7 µm). The etch characteristic of the SiC nanopillars under these conditions shows a high etch rate (550 nm min−1) and a high selectivity (over 60 for Ni). We also studied the etch profile of the SiC nanopillars and Mask evolution over the etching time. As the Mask Pattern size shrinks in nanoscale, vertical and lateral Mask erosion plays a crucial role in the etch profile of the SiC nanopillars. Long etching process makes the pillars appear with a hexagonal shape, coming from the crystallographic structure of α-SiC. It is found that the feature of pillars depends not only on the etching process parameters, but also on the crystallographic structure of the SiC phase.