Papers by Keyword: Crystal Quality

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Authors: Andrea Canino, Andrea Severino, Nicolò Piluso, Francesco La Via, Stefania Privitera, Alessandra Alberti
Abstract: 3C-SiC shows encouraging physical properties for the development of low cost high power compatible silicon based technology. The fundamental capability of grown 3C-SiC on silicon substrates leads to the possibility of a full integration of Si based process technologies. This is the driving force for the efforts for development a high quality heteroepitaxial film. The fundamental issue is the reduction of defects and stress due to the lattice mismatch between the 3C-SiC epilayer and the Silicon substrate. In this paper we show a way to reduce macroscopic structural features and to enhance the material quality and the surface quality by simply using a process based on a multilayer (ML) buffer structure with n++ and n doping alternation. This process leads to an evident improvement of both surface roughness, morphology and crystal quality.
Authors: Jung Doo Seo, Joon Ho An, Jung Gon Kim, Jung Kyu Kim, Myung Ok Kyun, Won Jae Lee, Il Soo Kim, Byoung Chul Shin, Kap Ryeol Ku
Abstract: SiC single crystal ingots were prepared onto different seed material using sublimation PVT techniques and then their crystal quality was systematically compared. In this study, the conventional SiC seed material and the new SiC seed material with an inserted SiC epitaxial layer on a seed surface were used as a seed for SiC bulk growth. The inserted epitaxial layer was grown by a sublimation epitaxy method called the CST with a low growth rate of 2μm/h. N-type 2”-SiC single crystals exhibiting the polytype of 6H-SiC were successfully fabricated and carrier concentration levels of below 1017/cm3 were determined from the absorption spectrum and Hall measurements. The slightly higher growth rate and carrier concentration were obtained in SiC single crystal ingot grown on new SiC seed materials with the inserted epitaxial layer on the seed surface, maintaining the high quality.
Authors: Toru Ujihara, S. Munetoh, Kazuhiko Kusunoki, Kazuhito Kamei, N. Usami, K. Fujiwara, G. Sazaki, Kazuo Nakajima
Authors: Ping Wu, Ejiro Emorhokpor, Murugesu Yoganathan, Thomas Kerr, Jie Zhang, Esteban Romano, Ilya Zwieback
Abstract: Several morphological defects in 4H SiC epitaxial wafers, including Comets and Triangles, may significantly impact on the yield and reliability of SiC devices. The formation of these epilayer defects is closely related to the substrate quality. This paper focuses on the study of the substrate quality and its relationship with defects in the epilayers. The crystalline quality of 4H n+ substrates has been characterized by x-ray diffraction, and the distribution of dislocations has been determined using etching in molten KOH. The relationship between Comet and Triangle epilayer defects and the dislocations has been established. A 10-fold reduction in the overall dislocation density in the 4H SiC substrates was achieved through technological improvements. The improvement was validated by the reduction in the number of the epilayer defects.
Authors: Hee Jun Lee, Hee Tae Lee, Hee Won Shin, Mi Seon Park, Yeon Suk Jang, Won Jae Lee, Im Gyu Yeo, Tai Hee Eun, Jang Yul Kim, Myoung Chul Chun, Si Hyun Lee, Jung Gon Kim
Abstract: The effect of the porous graphite plate above the source material on properties of silicon carbide (SiC) crystals grown by Physical Vapor Transport method has been investigated. The porous graphite plate was inserted on source powder to produce a more C-rich for the polytype stability of 4H-SiC crystal and a uniform radial temperature gradient. The dendrite structure obtained from SiC source powder in the crucible with porous graphite plate was more densely formed than that in the conventional crucible. The crystal quality of 4H-SiC single crystals grown in porous graphite inserted crucible was revealed to be better than that of crystal grown SiC crystals in the conventional crucible.
Authors: Doe Hyung Lee, Hee Tae Lee, Byung Joong Bae, Hee Jun Lee, Sang II Lee, Mi Seon Park, Won Jae Lee, Im Gyu Yeo, Tai Hee Eun, Myong Chuel Chun
Abstract: The present research was focused to extensively investigate the effect of TaC-coated crucible on the SiC crystal growth and then compare the difference of various properties between SiC crystals grown in conventional graphite crucible and TaC-coated crucible. The bulk growth was conducted around 2200°C of the growth temperature and 40 mbar of an argon atmosphere for the growth pressure. The better crystalline quality was obtained from the crystal grown in TaC-coated crucible. The SiC crystal grown in the TaC-coated crucible exhibited superior characteristics than SiC crystal grown in the conventional crucible in terms of the crystal quality and defect density. Furthermore, nitrogen incorporation in SiC crystal grown in the TaC-coated crucible was definitely decreased.
Authors: Hee Jun Lee, Hee Tae Lee, Hee Won Shin, Mi Seon Park, Yeon Suk Jang, Won Jae Lee, Dong Yeob Kim, Soon Ku Hong, Jung Gon Kim
Abstract: Aluminum nitride (AlN) bulk crystals, approximately 50.8mm in diameter and up to 5mm thickness, were grown by a physical vapor transport (PVT) method in a tantalum crucible. To investigate the effect of crucible materials, various crucible materials, a graphite and TaC-coated graphite and tantalum crucible were used for the AlN growth. XRD pattern of AlN crystal grown on SiC seed in the Ta-crucible exhibited only (00l) peaks, indicating that AlN single crystal was successfully grown on SiC seed. The interface structure between AlN and SiC crystals was observed by a high resolution TEM.
Authors: Hyun Hee Hwang, Jung Kyu Kim, Jong Mun Choi, Won Jae Lee, Il Soo Kim, Byoung Chul Shin, Hae Yong Lee
Abstract: GaN epitaxial layers were grown on sapphire substrate deposited an aluminum (Al) buffer layer using a hydride vapor phase epitaxy (HVPE) system with a two-zone resistance furnace. A 10nm-thick Al buffer layer was prepared by an e-beam evaporation in order to reduce the stress resulted from thermal mismatch between the GaN layer and the substrate. The growth temperature and growth rate for GaN epitaxial layer were 1050oC and 40 m/hr, respectively. GaN epitaxial layer grown on substrate with Al buffer layer exhibited uniform and smooth morphology on 2-inch whole substrate and a bow value of 33.5 m. The addition of Al-buffer layer apparently reduced the full width at half maximum (FWHM) value of GaN layer, which indicated the improvement of crystal quality.
Authors: Jung Gon Kim, Joon Ho An, Jung Doo Seo, Jung Kyu Kim, Myung Ok Kyun, Won Jae Lee, Il Soo Kim, Byoung Chul Shin, Kap Ryeol Ku
Abstract: We investigated the effects of hydrogen addition to the growth process of SiC single crystal using sublimation physical vapor transport (PVT) techniques. Hydrogen was periodically added to an inert gas for the growth ambient during the SiC bulk growth. Grown 2”-SiC single crystals were proven to be the polytype of 6H-SiC and carrier concentration levels of about 1017/cm3 was determined from Hall measurements. As compared to the characteristics of SiC crystal grown without using hydrogen addition, the SiC crystal grown with periodically modulated hydrogen addition definitely exhibited lower carrier concentration and lower micropipe density as well as reduced growth rate.
Authors: Kazutoshi Kojima, Toshiyuki Ohno, Seiji Suzuki, Junji Senzaki, Shinsuke Harada, Kenji Fukuda, Mitsuhiro Kushibe, Koh Masahara, Yuuki Ishida, Sadafumi Yoshida, Takaya Suzuki, Tetsuo Takahashi, Tomoyuki Tanaka, Kazuo Arai
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