A. Tanaka

Synthesis and growth of 3C-SiC crystals from solution at 950°C

Abstract In order to reduce the growth temperature of SiC crystals, Ga–Al–Si and/or Sn–Al–Si solution, in which the Si content was just below the saturation value, was reacted with C 3 H 8 gas at 950°C. After a 10xa0h-reaction, many small crystals were found in the solution. X-ray diffraction measurements revealed that the crystals are 3C-SiC. Using the wetting solution of these solutions, 3C-SiC crystal layers could be grown on a 6H-SiC substrate.

GaN crystal growth on an SiC substrate from Ga wetting solution reacting with NH3

Abstract A new method of GaN growth from Ga solution with NH 3 has been developed. The method is characterized by the use of a thin layer of Ga wetting solution formed on a rotating substrate and chemical reaction with NH 3 at the solution surface. The growth experiments, performed at 980°C with NH 3 supply rate of 9xa0sccm for 30xa0h, resulted in the layer mode growth of about 4xa0μm thickness on a part of Si-face of a 6H–SiC substrate. The thickness of wetting solution required for creating suitable super-saturation is discussed.

A numerical analysis for the conversion phenomenon of GaAs to GaAsP on a GaP substrate in an LPE system

Abstract A computational model for the mass transport occuring during the conversion of GaAs to GaAsP on a GaP substrate is presented. The mass transport equations in the liquid and solid phases, and the equations describing phase diagram constitute the governing equations. These equations together with appropriate interface and boundary conditions were solved numerically by the finite element method. Numerical solutions agree with experimental results and explain well the conversion phenomenon. The conversion process is initiated by the non-equilibrium condition between the Ga As P solution and the GaAs layer and promoted by the rapid diffusion of V elements into the GaAs (GaAsP conversion) layer.

Growth of GaInP thick layers by the modified yo-yo solute feeding method

Abstract A new process for the yo-yo solute feeding method has been developed to grow a thick Ga x In 1−x P alloy layer. In this process, we lowered the temperature of every cycle by 5°C. Only after three cycles was a Ga 0.69 In 0.31 P layer of about 70 μm in thickness epitaxially grown on a GaAsP(100) substrate. The thick layer shows the FWHM of PL (photoluminescence) peaks of 37.2 meV at 300 K and 13.7 meV at 4 K, which indicates high quality comparable with normal LPE-grown thin layers.

Formation of zinc blende GaN using the conversion technique

Abstract It has been found that GaAs grown on GaP substrate was converted to GaN by annealing in the flow of NH3. Using LPE, a GaAs layer of 5 μm thickness was grown on a GaP (111)B substrate. Then the GaAs layer was annealed in the flow of 100% NH3 for 30–60 min at 800–850°C. The GaAs layer was completely converted to GaN. X-ray diffraction measurements suggested that the GaN layer had mainly the zinc blende structure.

Rapid diffusion of V elements during the conversion of GaAs to GaAsP on a GaP substrate

Abstract A computational model for mass transport occurring during the conversion of GaAs to GaAsP on a GaP substrate is presented. The mass transport equations in the liquid and solid phases, and the phase diagram together with appropriate interface and boundary conditions were solved numerically by the finite element method. Numerical solutions agree with experimental results and explain well the conversion phenomenon. The conversion process is initiated by the non-equilibrium condition between the Gaue5f8Asue5f8P solution and the GaAs layer and promoted by the rapid diffusion of V elements into the GaAs (GaAsP conversion) layer. Further analysis shows that the period required for the conversion increases parabolically with increasing thickness of the GaAs layer.

Multilayered Graphene from SiC Films via Pyrolysis in Vacuum

1.Introduction Graphene is a carbon nano-system with two-dimensional layers of one-atom-thick, and have extraordinary electronic transport properties, which have attracted attention due to its potential for applications in nanoelectronics. Pyrolysis of SiC system in vacuum is known to be a very simple way for formation of grapene layers and multiwalled CNTs (MWNT). By using this method, we also have demonstrated single wall nanotubes (SWNTs) formation from single 6H-SiC substrates via hydrogenincorporated pyrolysis and multilayered graphene formation from amorphous SiC (a-SiC) films. However, there have been very few experimental results on carbon nano-system formation via pyrolysis in vacuum and its growth mechanism and controllability are controversial as yet. In this paper, we describe multilayerd graphene formation from SiC films grown by hot-wire MOCVD via pyrolysis in vacuum.

Conversion mechanism of GaAs to GaAsP on GaP substrate

Abstract A computational model for mass transport occurring during the conversion of GaAs to GaAsP on a GaP substrate is presented. The mass transport equations in the liquid and solid phases, and the phase diagram together with appropriate interface and boundary conditions were solved numerically by the finite element method (FEM). Numerical solutions agree with experimental results and explain well the conversion phenomenon.