Papers by Keyword: Growth from Vapor

Abstract: Physical vapour technique (PVT) is a versatile method to grow IIVI semiconductors. In present investigations, CdS crystals have been grown by this method using dual zone micro processor controlled horizontal furnace. CdS crystals grown in present case have been characterized by EDAX for stoichiometric conformation. The roughness of surface of grown CdS crystals has been studied in detail using optical microscopy, SEM and AFM. The surface topography study of as grown crystals has been carried out to understand the growth mechanism which was necessary for its application in electronic devices.

Abstract: Crystal growth velocity of SiC in a process of physical vapor transport was studied on the basis of numerical calculation including compressible effect, convection and buoyancy effects, flow coupling between argon gas and species, and the Stefan effect. Calculation in 2D configuration was performed to clarify the effect of pressure on growth velocity. The results revealed that the origin of diffusion resistance reported so far was the effect of convection of argon gas and chemical species.

Abstract: In this paper we present experimental results with the ion recombination process in the vapor phase growth method. We consider the growth process of only one element case, Zinc, because of the clarification of the change of electron states in the element, not the entropy effect due to different elements. The advantages of using the ion recombination process are the following; 1) controllability of total energy, 2) the highest quenching rate, 3) locality of the collision. The total energy of the ion system was below 240 eV. Zn^- ions exist on the growth front surface and Zn⁺ ones impinge to the growth surface from the vapor phase. The crystal structures of deposited zinc films are measured with the XRD system. Very strong diffuse scattering intensity of x-ray diffraction was observed at 10 eV, 90 eV, 100 eV and 230 eV after seven months “annealing” in room temperature from the preparation. These experimental facts suggest the effectiveness of the application of the excitation process of the inner core electron system as a new advanced material process. In this process, the ion recombination process and the existence of a metastable state are essentially important factors.

Abstract: Silicon carbide crystals were grown from the vapor. Improvement of the quality of the central part of the crystal was achieved by optimization of the geometry of the source material. Active thermal interaction of the source material and the crystallization front made possible an effective programming of the shape and morphology of the crystal. Termination of micropipes on microfacets formed on the crystallization front during growth was observed.

Abstract: The aim of the present work is to grow 3C-SiC on (0001) 6H-SiC seeds using the Physical Vapour Transport (PVT) method and to study the electrical and structural properties of the grown material. Photoluminescence (PL)-mappings reveal that the overgrown layer consists predominantly of the 3C-SiC polytype and capacitance-voltage (C-V) measurements result in a net nitrogen donor concentration of 1x1016cm-3. Transmission Electron Microscopy (TEM) observations also confirm that the overgrown layer is of the 3C-SiC polytype having the cubic [111] crystallographic direction parallel to the c-axis of the 6H-SiC substrate. In some cases, twin crystals of 3C-SiC are formed immediately after the interface and, in a few cases, small 6H-SiC inclusions are observed in the cubic film having the same orientation as the substrate. The film near the substrate/overgrown interface shows a high density of defects such as dislocations and stacking faults (SF’s), which propagate into the overgrown layer. Finally although there is a rapid decrease of the defect density within the first 60 µm from the interface, the SF density remains almost constant within the last 100 µm below the surface.