Papers by Keyword: Etch Pit

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Authors: Tomoaki Hatayama, Tetsuya Tamura, Hiroshi Yano, Takashi Fuyuki
Abstract: An etch pit shape of off-angled 4H-SiC Si-face formed by different halogen gases such as chlorine trifluoride (ClF3) and a mixed gas (O2+Cl2) of oxygen and chlorine in nitrogen (N2) ambience has been studied. One kind of etch pit with the crooked hexagon was formed at etching temperature under 500oC. The angle of etch pit measured by the cross-sectional atomic force microscope image was about 10o from the [11-20] view. A dislocation type of the etch pit was discussed in comparison with the etch pit shape and an X-ray topography image.
Authors: Hitoshi Habuka, Kazuchika Furukawa, Toshimitsu Kanai, Tomohisa Kato
Abstract: The etch pit density produced on the C-face 4H-SiC substrate using chlorine trifluoride gas at various temperatures was evaluated. Because the etch pit density formed at the substrate temperature of 713 K showed the comparable value to the current dislocation level of the Si-face 4H-SiC, the etch pit density obtained by this technique is considered to have a relationship with the crystal quality.
Authors: Hitoshi Habuka, Kazuchika Furukawa, Toshimitsu Kanai, Tomohisa Kato
Abstract: The etch pits on the C-face 4H-SiC substrate was produced by chlorine trifluoride gas at various temperatures. The etch pit density showed the comparable value to the current dislocation density level of the Si-face 4H-SiC, when the etching was performed around 713 K. Thus, the etch pit density obtained by this technique is expected to reveal the crystal quality.
Authors: Yong Zhao Yao, Yukari Ishikawa, Yoshihiro Sugawara, Daisaku Yokoe, Masaki Sudo, N. Okada, K. Tadatomo
Abstract: Threading dislocations (TDs) in an HVPE-grown free-standing GaN substrate have been studied by means of etch pit method using molten KOH+Na2O2 solution, cathodoluminescence (CL) mapping and transmission electron microscopy (TEM). We have focused on the correlation between (1) Burgers vectors of TDs, (2) their appearances as dark spots in CL image, and (3) geometries of corresponding etch pits. Based on the above results, dislocation categorization for GaN by using etch pits or CL is discussed.
Authors: Yong Zhao Yao, Yukari Ishikawa, Yoshihiro Sugawara, Koji Sato, Katsunori Danno, Hiroshi Suzuki, Hidemitsu Sakamoto, Takeshi Bessho, Satoshi Yamaguchi, Koichi Nishikawa
Abstract: In this paper, we report a newly developed dislocation-revealing etch pit method for 4H-SiC single crystal, which can distinguish edge (TED, Burgers vector b=a), elementary screw (TSD, b=1c) and mixed (TMD, b=c+a) threading dislocations. In this method, vaporized NaOH gas was used to etch the Si-face of a SiC wafer at substrate temperature around 950 °C. By a side-by-side comparison between the optical images of the etch pits and the X-ray topographic (XRT) images, it has been found that threading dislocations (TDs) in SiC could be revealed as hexagonal etch pits with distinct geometrical features (shape, size and facet orientation) depending on their Burgers vectors. Based on these results, we consider this etch pit method as an easily-operated and inexpensive technique to categorize TDs, and it may help to promote our understanding on the different roles that these types of TDs have played in the performance degradation of SiC power devices.
Authors: Hrishikesh Das, Galyna Melnychuk, Yaroslav Koshka
Abstract: Dislocations were investigated in the halo-carbon low-temperature epitaxial growth and low-temperature selective epitaxial growth (LTSEG) conducted at 13000C. The origin of triangular defects was investigated in low-temperature epilayers grown at higher growth rates with HCl addition. Due to the conversion of substrates’ basal plane dislocations (BPD) into threading dislocations, the concentration of BPDs was about an order of magnitude lower than the concentration of threading dislocations at moderate growth rates. An additional order of magnitude conversion of BPDs into threading dislocations was observed at higher grow rates achieved with HCl addition. In LTSEG epilayers, dislocation concentration away from the mesa walls was comparable to the blanket (i.e., regular non-selective) growth. High concentrations of BPDs were found only at mesa edges located on the “upstream” side with respect to the step-flow direction. No substrate defects could be traced to the triangular defects. Instead, the disturbances causing the triangular defect generation are introduced during the epitaxial process.
Authors: Yong Zhao Yao, Yukari Ishikawa, Yoshihiro Sugawara, Koji Sato, Katsunori Danno, Takayuki Shirai, Kazuaki Sato, Takeshi Bessho, Yumiko Takahashi, Yoshiki Yamashita, Keiichi Hirano
Abstract: Threading dislocations (TDs) in 4H-SiC have been studied by comparing etch pits formed by NaOH vapor etching with results of synchrotron monochromatic-beam X-ray topography (XRT) taken under different g-vectors. Burgers vectors determined based on XRT results were utilized to investigate the etch pit characteristics of edge (TED), screw (TSD) and mixed (Burgers vector b=c+a, TMD) threading dislocations. It has been found that pit formation by NaOH vapor etching was very different to that by conventional molten KOH etching. We discuss the possibility of using NaOH vapor etching to distinguish TMDs from TSDs, and report a variety of characteristic etch pits formed by this method and their correlations to dislocation behavior.
Authors: Jae Kwang Lee, Yun Ho Shin, Jin Wook Kang, Yong Sug Tak
Abstract: The effect of chemical pretreatments on the electrochemical etching behavior of aluminum was investigated with the topographic studies of surface and the analysis of initial potential transients. Two-step pretreatments with H3PO4 and H2SiF6 result in a high density of pre-etch pits on aluminum surface by the incorporation of phosphate ion inside the oxide film and the removal of surface layer by aggressive fluorosilicic acid solution. It generates a high density of etch pits during electrochemical etching and results in the capacitance increase of etched Al electrode by expanding the surface area, up to 61.3 μF/cm2 with the pretreatment solution of 0.5M H3PO4 at 65°C and 10 mM H2SiF6 at 45°C.
Authors: Jae Han Jeong, Sung Su Kim, Hyun Gi Kim, Chang Hee Choi, Dong Nyung Lee
Authors: M. Kayambaki, Konstantinos Zekentes, Katerina Tsagaraki, Etienne Pernot, Rositza Yakimova
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