The Experts below are selected from a list of 11310 Experts worldwide ranked by ideXlab platform
Dimitrios Maroudas - One of the best experts on this subject based on the ideXlab platform.
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Surface Smoothness of plasma deposited amorphous silicon thin films Surface diffusion of radical precursors and mechanism of si incorporation
Physical Review B, 2006Co-Authors: Mayur S Valipa, Tamas Bakos, Dimitrios MaroudasAbstract:We present a detailed analysis of the fundamental atomic-scale processes that determine the Surface Smoothness of hydrogenated amorphous silicon (a-Si:H) thin films. The analysis is based on a synergistic combination of molecular-dynamics (MD) simulations of radical precursor migration on Surfaces of a-Si:H films that are deposited computationally using MD simulation with first-principles density functional theory (DFT) calculations on the hydrogen-terminated $\mathrm{Si}(001)\text{\ensuremath{-}}(2\ifmmode\times\else\texttimes\fi{}1)$ Surface. The Surfaces of the MD-grown a-Si:H films are remarkably smooth, as the mobile precursor, the $\mathrm{Si}{\mathrm{H}}_{3}$ radical, diffuses fast and incorporates in Surface valleys. Analysis of the MD simulations of $\mathrm{Si}{\mathrm{H}}_{3}$ radical migration on a-Si:H Surfaces yields an effective diffusion barrier of $0.16\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The low diffusion barrier on the a-Si:H Surface is attributed to $\mathrm{Si}{\mathrm{H}}_{3}$ migration through overcoordinated Surface Si atoms, where the radical remains weakly bonded to the Surface at all times and does not break any strong Si-Si bonds along its migration pathway. Furthermore, the diffusing $\mathrm{Si}{\mathrm{H}}_{3}$ radical incorporates into the a-Si:H film only when it transfers an H atom and forms a second Si-Si backbond. On rough a-Si:H films, such H transfer from diffusing $\mathrm{Si}{\mathrm{H}}_{3}$ radicals is more likely to occur in Surface valleys, even when the dangling bond (DB) density is low and DBs are not present in Surface valleys. In addition, this H-transfer process is thermally activated with activation energy barriers $({E}_{a})$ over the range $0.29--0.65\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$; ${E}_{a}$ is determined by the Si-Si interatomic distance between the Si of the $\mathrm{Si}{\mathrm{H}}_{3}$ radical and the Surface Si atom to which the H is transferred. The preferential incorporation in valleys is explained by both the increased residence time of the migrating precursor in valleys and the decreased activation barrier for incorporation reactions occurring in valleys. The mechanism and activation barrier for the H-transfer reaction on the a-Si:H Surface were validated by performing first-principles DFT calculations on the crystalline Si Surface.
Franklin Chaunan Hong - One of the best experts on this subject based on the ideXlab platform.
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growth of diamond films with high Surface Smoothness
Diamond and Related Materials, 2006Co-Authors: Shr Ming Huang, Franklin Chaunan HongAbstract:Abstract Diamond films with highly smooth backside Surface have been deposited by positively biasing the substrate during diamond growth in a hot-filament chemical vapor deposition (HFCVD) system. By bonding the diamond film on the glass and wet etching to remove silicon, the highly smooth diamond Surface can be exposed and used directly for the fabrication of diamond devices. Silicon substrate was first treated by diamond powder of 625 nm in an ultrasonic bath. By positively biasing the substrate, electron bombardment during diamond growth increases the nucleation density from 108 ∼ 109 cm− 2 to 4 × 1011 cm− 2. The Surface Smoothness on the backside of diamond film has thus been improved significantly, inducing root-mean-square roughness of 5 nm. Owing to the extremely high Surface Smoothness and the high crystalline quality on the backside of diamond film and the high diamond growth rate, the backside Surface of the diamond film grown under electron bombardment is particularly suitable for device fabrication.
Mayur S Valipa - One of the best experts on this subject based on the ideXlab platform.
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Surface Smoothness of plasma deposited amorphous silicon thin films Surface diffusion of radical precursors and mechanism of si incorporation
Physical Review B, 2006Co-Authors: Mayur S Valipa, Tamas Bakos, Dimitrios MaroudasAbstract:We present a detailed analysis of the fundamental atomic-scale processes that determine the Surface Smoothness of hydrogenated amorphous silicon (a-Si:H) thin films. The analysis is based on a synergistic combination of molecular-dynamics (MD) simulations of radical precursor migration on Surfaces of a-Si:H films that are deposited computationally using MD simulation with first-principles density functional theory (DFT) calculations on the hydrogen-terminated $\mathrm{Si}(001)\text{\ensuremath{-}}(2\ifmmode\times\else\texttimes\fi{}1)$ Surface. The Surfaces of the MD-grown a-Si:H films are remarkably smooth, as the mobile precursor, the $\mathrm{Si}{\mathrm{H}}_{3}$ radical, diffuses fast and incorporates in Surface valleys. Analysis of the MD simulations of $\mathrm{Si}{\mathrm{H}}_{3}$ radical migration on a-Si:H Surfaces yields an effective diffusion barrier of $0.16\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. The low diffusion barrier on the a-Si:H Surface is attributed to $\mathrm{Si}{\mathrm{H}}_{3}$ migration through overcoordinated Surface Si atoms, where the radical remains weakly bonded to the Surface at all times and does not break any strong Si-Si bonds along its migration pathway. Furthermore, the diffusing $\mathrm{Si}{\mathrm{H}}_{3}$ radical incorporates into the a-Si:H film only when it transfers an H atom and forms a second Si-Si backbond. On rough a-Si:H films, such H transfer from diffusing $\mathrm{Si}{\mathrm{H}}_{3}$ radicals is more likely to occur in Surface valleys, even when the dangling bond (DB) density is low and DBs are not present in Surface valleys. In addition, this H-transfer process is thermally activated with activation energy barriers $({E}_{a})$ over the range $0.29--0.65\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$; ${E}_{a}$ is determined by the Si-Si interatomic distance between the Si of the $\mathrm{Si}{\mathrm{H}}_{3}$ radical and the Surface Si atom to which the H is transferred. The preferential incorporation in valleys is explained by both the increased residence time of the migrating precursor in valleys and the decreased activation barrier for incorporation reactions occurring in valleys. The mechanism and activation barrier for the H-transfer reaction on the a-Si:H Surface were validated by performing first-principles DFT calculations on the crystalline Si Surface.
X. Yuan - One of the best experts on this subject based on the ideXlab platform.
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UV induced controllable volume growth in hybrid sol-gel glass for fabrication of a refractive microlens by use of a grayscale mask
Optics Express, 2003Co-Authors: Weixing Yu, X. YuanAbstract:We report a simple method for forming Surface corrugation of microlenses based on a volume growth effect of sol-gel glass. The volume growth effect was fully calibrated with a high-energy beam-sensitive grayscale mask, where the amount of growth was determined as a function of electron-beam-induced optical densities in the mask. This technique provides an excellent Surface Smoothness compared with other development based fabrication techniques. For example, a refractive microlens with a diameter of 140 microm and a sag height of 2.13 microm was demonstrated.
Sok-hyun Kong - One of the best experts on this subject based on the ideXlab platform.
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Multilayered soft magnetic underlayers for perpendicular magnetic recording media
Joint NAPMRC 2003. Digest of Technical Papers, 2003Co-Authors: S. Nakagawa, T. Okamoto, Sok-hyun KongAbstract:The soft magnetic underlayer (SUL) with high saturation magnetization in perpendicular magnetic recording media have been required essentially to achieve high recording density with high bit stability. However, stripe domain configuration caused by the induced perpendicular magnetic anisotropy and deterioration of Surface Smoothness in thick SULs degrades the recording performance. In this study, multilayers, with several kinds of interlayers for the SUL, were prepared in order to improve the soft magnetic properties and Surface Smoothness as well as reduce the media noise originated from the domain configuration.
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Soft magnetic underlayer with multilayer structure for perpendicular magnetic recording media
2003 IEEE International Magnetics Conference (INTERMAG), 2003Co-Authors: Sok-hyun Kong, T. Okamoto, S. NakagawaAbstract:In this study, multilayers with non-magnetic interlayers for the SUL were prepared in order to improve the soft magnetic properties and Surface Smoothness as well as reduce the media noise originated from the configuration.
