Papers by Keyword: n-Type Doping

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Authors: Keisuke Fukada, Naoto Ishibashi, Yoshihiko Miyasaka, Akira Bandoh, Kenji Momose, Hiroshi Osawa
Abstract: The depth profiles of n-type doping concentration in thick (>100 μm) and low-doped (< 4 × 1014 cm-3) 4H-SiC epilayers grown by chemical vapor deposition (CVD) were investigated. The variation in doping concentration during epitaxial growth are considered to be caused by: (1) variation in gas flow due to parasitic deposition, (2) variation in precursor decomposition rate due to change in reactor temperature, (3) variation in dopant incorporation rate due to change in wafer temperature, and (4) variation in supply of background dopants. By controlling all these parameters, a constant depth profile in thick (> 100um) epilayers was realized.
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Authors: C.X. Xu, X.W. Sun, Z.L. Dong, G.P. Zhu, Y.P. Cui
Abstract: In this paper, field emission from ZnO was studied by morphological and electronic design. By fabricating ZnO into nanopin structure with sharp tip, we can obtain low threshold and high emission current density. By doping ZnO with gallium, we can lift up the Fermi level and increase the conductivity to enhance the field emission. The fabrication of nanostructures and analysis of field emission will be discussed.
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Authors: Yoshiaki Daigo, Akio Ishiguro, Shigeaki Ishii, Hideki Ito
Abstract: In this study, influence of both Si/H2 ratio and C/Si ratio on growth rate uniformity and carrier concentration uniformity of n-type 4H-SiC epitaxial films grown by high speed wafer rotation vertical CVD tool was investigated. It was found that changes in radial profile of the growth rate and the carrier concentration obtained by varying Si/H2 ratio showed quite similar behavior to those obtained by varying C/Si ratio. Such a similar trend would suggest that the distribution of local C/Si ratio near the wafer surface changes depending on total Si/H2 ratio similarly to total C/Si ratio. Additionally, by using this relationship, both the growth rate uniformity of 49.2 μm/h ±1.78% (1.15% σ/mean) and carrier concentration uniformity of 1.08 ×1016cm-3 ±6.15% (3.40% σ/mean) was achieved.
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Authors: Yan Cai, Jurgen Michel
Abstract: We review two ex-situ doping methods to achieve high n-type doping up to mid-1019 cm-3 in Ge-on-Si thin films. For both, delta doping and ion implantation, rapid thermal annealing is used to diffuse phosphorus from a diffusion source into the single crystal Ge layer. The diffusion mechanism is studied and we find that dopant enhanced diffusion in in-situ doped Ge attributes to the high doping level. A band gap narrowing effect is observed in highly doped n-type Ge through photoluminescence measurements by determining the photoluminescence peak shift. An empirical linear expression of the direct band gap narrowing shift with carrier concentration is proposed.
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Authors: Marcin Zielinski, Thierry Chassagne, Roxana Arvinte, Adrien Michon, Marc Portail, Sylvie Contreras, Sandrine Juillaguet, Hervé Peyre
Abstract: After presenting an exhaustive experimental study of aluminum incorporation in epitaxial 4H-SiC and 3CSiC films grown by chemical vapor deposition (CVD), we focalize once more on what is called site competition effects. We observed that the influence of C/Si ratio on dopant (Al, N) incorporation in SiC was qualitatively different depending on whether the growth experiments were performed in “low temperature” (LT) or “high temperature” (HT) regime. Partial explanation of observed phenomena basing on thermal evolution of carbon coverage of SiC surface is proposed.
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Authors: Zhe Chuan Feng, S.J. Chua, A.G. Evans, John W. Steeds, K.P.J. Williams, G.D. Pitt
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Authors: S.O. Ferreira, W. Faschinger, H. Sitter
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Authors: Urban Forsberg, Anne Henry, Margareta K. Linnarsson, Erik Janzén
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Authors: Irina G. Galben-Sandulache, Maya Marinova, Alkyoni Mantzari, Guoli L. Sun, Ariadne Andreadou, Didier Chaussende, Efstathios K. Polychroniadis
Abstract: This work presents the crystalline quality investigation of 3C-SiC unseeded crystals grown from vapor phase. Samples were polished after different crystallographic planes from crystals grown with or without nitrogen flow. The structural and optical investigation showed that the central part of the samples exhibited a very good crystalline quality. The best samples proved to be the {100} growth sectors where the only defects found were stacking faults with a defect density under 103 cm-1. At the edges, i.e. between two adjacent growth sectors, structural investigation by transmission electron microscopy revealed stacking faults and hexagonal polytype inclusions. The nitrogen doping was found not to have an influence on the crystalline quality.
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Authors: William W. Sullivan III, Cameron Hettler, James Dickens
Abstract: This paper investigates n-type doping of point-defect compensated high purity semi-insulating (HPSI) 4H-SiC using a pulsed laser (10 ns FWHM @ 260 nm) for the introduction of nitrogen to shallow depths. A thermal model is presented using COMSOL Multiphysics featuring nonlinear temperature dependent material properties and a volumetric heat source term that takes into account the laser absorption depth for common ultraviolet irradiating wavelengths. The temperature distribution in the material and the amount of time that the surface and near-surface regions are at high temperature determines how many laser pulses are required to dope to the desired depth, and simulation results are presented and fit to measured data. The simulations and measured data show that for shallow doping a short wavelength ultraviolet laser should be used to localize the heat at the surface so the dopant can’t diffuse deep into the material. The laser enhanced diffusion process has been used to incorporate nitrogen into HPSI 4H-SiC with a measured surface concentration greater than 1020 cm-3 and a nonlinear thermal model was built.
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