Papers by Keyword: C/Si Ratio

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Authors: Hiroaki Saitoh, Tsunenobu Kimoto
Abstract: Chemical vapor deposition of 4H-SiC on (0001) substrates with various off-angles from 1o to 45o has been investigated. On large-off-angled (15o-45o) substrates, very smooth surface morphology is obtained in the wide range of C/Si ratio. The micropipe dissociation during epitaxial growth is observed on 4o-45o off-angled substrates with a low C/Si ratio. The incorporation of nitrogen was dramatically suppressed by increasing C/Si ratio irrespective of substrate’s off-angle.
Authors: Giovanni Attolini, Bernard Enrico Watts, Matteo Bosi, Francesca Rossi, Ferenc Riesz
Abstract: A comparative study of the morphology of 3C-SiC films prepared with different C:Si ratios is presented. The silane precursor controls the growth rate at all values of C:Si ratio but combined of observations using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) indicates that the C:Si ratio is critical in determining the grain size and at values of C:Si close to 1 texturing and faceting become evident. Makyoh Topography reveals various surface defects, a slight mesoscale roughness and bending of the epiwafers.
Authors: S. Hahn, Franziska Christine Beyer, Andreas Gällström, Patrick Carlsson, Anne Henry, Björn Magnusson, J.R. Niklas, Erik Janzén
Abstract: The novel technique microwave detected photo induced current transient spectroscopy (MD-PICTS) was applied to semi-insulating 6H-SiC in order to investigate the properties of inherent defect levels. Defect spectra can be obtained in the similar way to conventional PICTS and DLTS. However, there is no need for contacting the samples, which allows for non-destructive and spatially resolved electrical characterization. This work is focused on the investigation of semi-insulating 6H-SiC grown under different C/Si-ratios. In the corresponding MD-PICTS spectra several shallow defect levels appear in the low temperature range. However the peak assignment needs further investigation. Additionally different trap reemission dynamics are obtained for higher temperatures, which are supposed to be due to different compensation effects.
Authors: Isaho Kamata, Hidekazu Tsuchida, Syunsuke Izumi, Takeshi Tawara, Kunikaza Izumi
Authors: Kazutoshi Kojima, Keiko Masumoto, Sachiko Ito, Akiyo Nagata, Hajime Okumura
Abstract: We have investigated key factors for controlling the polytype and surface morphology of 4H-SiC homoepitaxial growth on less than 4o off-axis substrates. In addition, we characterized the crystal quality and surface quality of the epitaxial layer of an entire 3-inch vicinal off angled substrate. The results suggested that the control of surface free energy, control of the vicinal off angle itself, and high temperature growth, is highly important in controlling the surface morphology and polytype stability of the epitaxial layer grown on a vicinal off angled substrate. We also obtained a high-quality epitaxial layer grown on a 3-inch vicinal off angle substrate, which was comparable to those on 4o off-axis substrates.
Authors: Hai Zheng Song, M.V.S. Chandrashekhar, T.S. Sudarshan
Abstract: Application of dichlorosilane (DCS) in 4H-SiC epitaxial growth on 4° off-cut substrates has been studied. The effect of C/Si ratio and N2 gas flow rate on epilayer properties is investigated in detail. It is found that the C/Si ratio has a significant influence on the growth rate, epilayer surface roughness (step-bunching), conversion of basal plane dislocations (BPDs), and generation of morphological defects and in-grown stacking faults. A wide range of doping concentration from p- to n+ can be controlled in DCS growth. High quality 4° off-cut SiC epilayers are achieved for C/Si=1.3 – 1.8. Addition of N2 has no obvious influence on growth rate and defect densities. The BPD conversion greater than 99.8% is achieved independent of N doping without any pretreatment.
Authors: René A. Stein, Bernd Thomas, Christian Hecht
Abstract: Epitaxial layers have been grown on the (0001) C-face of 2- and 3-inch 4H-SiC wafers. Growth conditions like temperature, pressure, and C/Si ratio have been varied. In both systems smooth surface morphologies could be obtained. The main challenge of epitaxial growth on the Cface of 4H-SiC for electronic device applications seems to be the control of low doping concentration. High temperature and low pressure are the key parameters to reduce the nitrogen incorporation. The hot-wall CVD system used for these experiments allowed the application of higher temperatures and lower pressures than the cold-wall equipment. The lowest doping concentration of 2.5x1015 cm-3 has been achieved by hot-wall epitaxy using a temperature of 1625 °C, a system pressure of 50 hPa, a C/Si ratio of 1.4, and a growth rate of 6.5 2mh-1. Good doping homogeneity on 2-inch and 3-inch wafers could be achieved. For a doping level of ND-NA= 3×1015 cm-3 sigma is about 15%.
Authors: Ling Guo, Koji Kamei, Kenji Momose, Hiroshi Osawa
Abstract: In this study, we investigated the epitaxial surface defects resulting from the carbon-inclusion defects in 4H-SiC substrate. Most carbon-inclusion defects developed into one of three types of epitaxial surface defects under normal epitaxial growth conditions. Among them, we found a regular hexagonal pit by high-resolution microscopy, which we regarded as a large-pit defect, and which had an adverse impact on the reverse electrical characteristics of Schottky barrier diodes. Conversion of a carbon-inclusion defect to a large-pit defect or a triangular defect could be reduced by reducing the C/Si ratio.
Authors: Yong Qiang Sun, Gan Feng, Jun Yong Kang, Wei Ning Qian, Li Ping Lv, Yi Yang Li, Kai Xi Li, Jian H. Zhao
Abstract: The large growth pits (LGPs) dependence of substrate quality, growth rate, and C/Si ratio have been discussed in the 4H-SiC epitaxial growth on 100 mm N-type 4H-SiC Si-face substrates misoriented by 4° toward [11-20] with a warm-wall planetary reactor. The formation and reduction of LGPs have been investigated by adjusting the growth process parameters. With the optimized process, the perfect surface morphology with lower LGPs density has been obtained on the high quality substrate.
Authors: Mitsuo Okamoto, Yasunori Tanaka, Ryouji Kosugi, Daisuke Takeuchi, Shinichi Nakashima, Shin Ichi Nishizawa, Kenji Fukuda, Hideyo Okushi, Kazuo Arai
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