Papers by Keyword: Antiphase Boundary (APB)

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Authors: S. Takahashi, Naoya Tada, A.Y. Takahashi
Authors: Hiroyuki Nagasawa, Kuniaki Yagi, Takamitsu Kawahara, Naoki Hatta, Masayuki Abe, Adolf Schöner, Mietek Bakowski, Per Ericsson, Gerhard Pensl
Abstract: In 3C-SiC MOSFETs, planar defects like anti-phase boundaries (APBs) and stacking-faults (SFs) reduce the breakdown voltage and induce leakage current. Although the planar defect density can be reduced by growing 3C-SiC on undulant-Si substrate, specific type of SFs, which expose the Si-face, remains on the (001) surface. Those SFs increase the leakage current in devices made with 3C-SiC. In order to eliminate the residual SFs, an advanced SF reduction method involving polarity conversion and homo-epitaxial growth was developed. This method is called switch-back epitaxy (SBE) and consists of the conversion of the SF surface polarity from Si-face to C-face and following homo-epitaxial growth. The reduction of the SF density in SBE 3C-SiC results in a tremendous improvement of the device performance. The combination of the achieved blocking voltage with the demonstrated high current capability indicates the potential of 3C-SiC vertical MOSFETs for high and medium power electronic applications such as electric and hybrid electric vehicle (EV/HEV) motor drives.
Authors: Hiroyoki Nagasawa, Ramya Gurunathan, Maki Suemitsu
Abstract: Eelectrically active defects in 3C–SiC are investigated by considering the structures and interactions of planar defects. An anti-phase boundary (APB) largely degrades the blocking property of semiconductor devices due to its semimetallic nature. Although APBs can be eliminated by orienting the specific polar face of 3C-SiC along a particular direction, stacking faults (SFs) cannot be eliminated due to Shockley-type partial dislocation glide. SFs with Shockley-type partial dislocations form a trapezoidal plate which expands the Si-terminated surface with increasing 3C-SiC thickness. Although the density of SFs can be reduced by counter termination, specific cross-junctions between a pair of counter SFs forms a forest dislocation, and this is regarded as an electrically active defect. This paper proposes an effective way to suppress the forest dislocations and APBs which nucleate during 3C-SiC growth.
Authors: Kuniaki Yagi, Hiroyuki Nagasawa
Authors: M. Eickhoff, N. Vouroutzis, A. Nielsen, G. Krötz, J. Stoemenos
Authors: Mikhail Starostenkov, Alexandra Chaplygina, Veronika Romanenko
Abstract: Alloys of Cu-Pt [1] are of interest for research, since the phase transitions "order - disorder" at different concentrations of components form several types of superstructures. In the alloy Cu3Pt the ordering L12 superstructure formed on the basis of fcc lattice. In the ordering of the fcc lattice of the disordered solid solution the equiatomic composition transformed into the L11 superstructure with an rhombohedral crystal lattice (a state with an L11, whose angles α, β, and γ are other than π/2). A CuPt3 in an ordered state has an L13 superstructure (a state with an L13, whose angles α, β, and γ are other than π/2). A possible existence of an ordered phase containing 20 at.% Pt was reported in the literature [2], which corresponds to the composition of Cu4Pt (type of superstructure was not defined). In other sources, an occurrence of an ordered compound, Cu7Pt, was predicted, containing 12.5 at.% Pt [3]. Computer experiments performed on the Monte Carlo method, showed that the alloys of the Cu - Pt different composition components undergo phase transformations "disorder - order" from the FCC to the structures of different symmetry [4,11]. This paper presents the results of a study of the structural transformations in the alloys Cu3Pt, CuPt, CuPt3 (superstructure L12, L11, L13), containing shear antiphase boundaries (APB) in the planes {111}.
Authors: Hiroyuki Y. Yasuda, T. Kase, S. Minamiguchi, A. Yokoyama, Yukichi Umakoshi, P.M. Bronsveld, Jeff T.M. de Hosson
Abstract: The pseudoelastic behavior of Fe3Al single crystals doped with an extra element (e.g. Ti, V, Cr, Mn, Co, Ni, Si, Ga, Ge) was investigated. In binary Fe-23.0at.%Al crystals with the D03 structure, 1/4[111] superpartial dislocations moved independently dragging the nearest-neighbor anti-phase boundaries (NNAPB) during loading. During unloading, the NNAPB pulled back the superpartials decreasing its energy resulting in a giant pseudoelasticity of which the recoverable strain is about 5 %. Addition of a third element significantly affected the pseudoelastic behavior of Fe3Al single crystals. Mn- or Ga-doped crystal demonstrated a giant pseudoelasticity. In particular, Ga-doping was found to be effective in the enhancement of the pseudoelasticity. On the other hand, the amount of strain recovery decreased upon doping of the other elements. The frictional stress of the superpartials, the back stress of the NNAPB and ordered domain structure in the crystals changed upon doping, which was closely related to the pseudoelastic behavior.
Authors: Hiroyuki Y. Yasuda, Tsuyoshi Furuta, Takenori Maruyama
Abstract: Pseudoelasticity of Fe3Ga polycrystals doped with third elements (Ti, V, Cr, Mn, Co, Ni, Si, Ge) was examined. Fe3Ga polycrystals with the appropriate heat treatment were found to exhibit large pseudoelasticity based on reversible motion of dislocation dragging an antiphase boundary (APB). In Fe3Ga crystals with the D03 superlattice structure, paired 1/4<111> superpartial dislocations mainly moved dragging the next-nearest-neighbor APB during loading. During unloading, the APB pulled back the superpartial dislocations resulting in the pseudoelasticity. The D03 ordered phase also developed in Fe3Ga polycrystals with 2at% of the third elements. However, the strain recovery of Fe3Ga polycrystals depended strongly on third element. Fe3Ga polycrystals doped with 2at% of Mn, Cr and Co demonstrated large pseudoelasticity. In contrast, the other doped elements decreased the amount of strain recovery. The frictional stress of 1/4<111> superpartial dislocations and the back stress due to the APB, acting on the dislocations, changed by doping the third elements, which was closely related to the pseudoelastic behavior. It is also noted that there was a good correlation between the APB back stress and the ordering temperature from the B2 to D03 phase.
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