Sakiko Kawanishi

Fe-Si melt is a candidate for use as an alloy solvent for rapid liquid phase growth of SiC because of the high solubility of carbon in molten iron. In this work, the equilibrium phase relationship between SiC and the liquid phase of the Fe-Si-C system was studied to determine the optimal composition of a high SiC content solvent. The solubility of carbon in molten silicon was examined and the thermodynamic properties of the liquid phase in the Si-C system were reassessed. The phase relationship

We report the growth of large Cl-doped and Br-doped SnS single crystals from a molten Sn-based flux. Compared with the small and lamellar undoped SnS crystals, the addition of SnCl2 or SnBr2 halogen sources in the flux substantially enhanced lateral growth along the (100)-plane and vertical growth. The maximum size of the obtained single crystals reached a diameter and thickness of 16 mm and 0.7 mm for the Cl-doped SnS and 24 mm and 1.0 mm for the Br-doped SnS, respectively. The X-ray rocking cu

Microscopic real-time observation of the solution growth interface of SiC using Fe–Si solvent at 1673 K was successfully performed to understand the interface morphology at the initial stage of solution growth. The growth interface was composed of a number of domains with step–terrace structures originating from either spiral growth of 4H-SiC or two-dimensional island growth of other polytypes. The validity of the measurements of the step structures by bright-field and interference images was co

Real-time observation of the high temperature interface between silicon carbide (SiC) and liquid alloy is indispensable to optimize the conditions for producing high quality SiC crystals by the solution growth method. In this work, real-time observation of the interface was established by using the interference observation to measure the height profile of the interface. The temperature dependence of the refractive index of 4H-SiC was measured up to 1773 K. The height measurement was then carried

The equilibrium phase relations of molten Si–Fe, Si–Ni, and Si–Fe–Cr alloys saturated with either silicon carbide (SiC) or graphite, which are candidates for the solvent for rapid solution growth of SiC, have been investigated. The measured carbon solubilities at 2073 K were 0.19–6.6 mol% for the Si–(24.1–70.1) mol% Fe, 0.061–5.2 mol% for Si–(30.0–85.0) mol% Ni, and 1.1–3.9 mol% for Si–(50−x) mol% Fe–x mol% Cr (x = 10.4–40.1) alloys. A quasi-chemical model that assumes that the carbon atoms are

The melt-back process has a significant effect on the quality of solution-grown SiC crystals. However, the phenomena surrounding the SiC dissolution into the molten alloy during the melt-back process have not been clarified. In this study, the behavior of 4H-SiC dissolution into molten alloy was investigated by using high-temperature in situ observation and subsequent KOH etching, and the effects of different doping conditions and crystal polarity were studied. Local dissolutions with hexagonal

A new process for the fabrication of double positioning boundary (DPB) free 3C-SiC was demonstrated by utilizing the threading screw dislocations of 6H-SiC, using the following two steps: (1) formation of a spiral structure with six bilayer steps on a seed 6H-SiC; and (2) nucleation of 3C-SiC on the seed. In the first step, the six-bilayer step structure was formed via spiral dissolution using a molten Fe–Si alloy. The formation of a spiral structure on both the 6H-SiC (0001) and (0001̅) faces c

To obtain fundamental knowledge on the behavior of magnesium (Mg) and calcium (Ca) in solid silicon (Si) during solidification, the solid solubilities of Mg and Ca in Si were reinvestigated by temperature-gradient zone melting method. Solubilities were measured to be 0.0016–0.0041 mol% for Mg and 0.0006–0.0021 mol% for Ca at 1373–1623 K. The excess Gibbs energies of Mg and Ca in solid Si were determined from their solid solubilities as follows: