Papers by Keyword: Sublimation Epitaxy

Abstract: Free standing 3C-SiC wafers with a dimeter of 50 mm and a thickness of ca. 0.8 mm have been grown on a regular base using 3C-SiC CVD seed transfer from Si wafers to a poly-SiC-carrier and a sublimation epitaxy configuration. Up to the thickness of almost 1 mm, stable growth conditions of the cubic polytype have been achieved. The high supersaturation was kept stable by the proper design of the hot zone that enables a high axial temperature gradient at the growth interface. The Sirich gas phase was realized by the application of a Tantalum getter that was integrated into the graphitebased growth cell. Furthermore, an adaption of the growth setup allowed the growth of 3C material with a diameter of 95 mm and bulk material up to 3 mm on 25 mm diameter. Computer simulations were used to determine the supersaturation of the growth setup for different source-to-seed distances. The minimum supersaturation necessary for stable growth of cubic SiC was found to be higher 0.1 for seed already containing the required 3C polytype.

Abstract: We present three different ways of transferring 3C-SiC layers grown on silicon on top of a SiC carrier using a carbon glue layer. Our main focus was upon the growth on the transition layer, as 3C-SiC does not feature any polarities in the <100> or <-100> direction. We realized a stable and reproducible process by following a wet chemical approach, dealing with the difficulties of handling thin but freestanding 3C-SiC layers. By using this way, we transferred approximately 130 μm thick pieces using their horizontal hot-wall reactor (M10), which were chemo mechanically polished and afterwards fixed on our SiC carriers. Implementing such a seeding stack into our growth setup, we managed to grow between 20 μm and 130 μm thick layers on top. We have proven the possibility to grow on the transition layer. Furthermore, we observed a slight reduction in protrusion density, which is currently one of the main defects in such layers.

Abstract: 300 μm thick 3C-SiC epilayer was grown on off-axis 4H-SiC(0001) substrate with a high growth rate of 1 mm/hour. Dry oxidation, wet oxidation and N₂O anneal were applied to fabricate lateral MOS capacitors on these 3C-SiC layers. MOS interface obtained by N₂O anneal has the lowest interface trap density of 3~4x10¹¹ eV^-1cm^-2. Although all MOS capacitors still have positive net charges at the MOS interface, the wet oxidised sample has the lowest effective charge density of ~9.17x10¹¹ cm^-2.

Abstract: We investigated three 3C-SiC samples grown on 6H SiC substrate by sublimation epitaxy under gas atmosphere. We focus on the low temperature photoluminescence and Raman measurements to show that compare to a growth process under vacuum atmosphere, the gas atmosphere favor the incorporation of impurities at already existing and/or newly created defect sites.

Abstract: Transmission electron microscopy and the cathodoluminescence method have been used to study the transition region in 3C-SiC/6H-SiC heterostructures. It is shown that this region is, as a rule, constituted by alternating 3C-SiC and 6H-SiC layers, with possible inclusion of other silicon carbide polytypes. An assumption is made that this structure of the transition region can be explained in terms of the spinodal decomposition model

Abstract: Abstract Results of an epitaxial growth of 3C-SiC epilayers on Si (0001) and C(000¯1) faces of hexagonal 6H-SiC substrates are described. TEM study of grown layers as well as interface between cubic and hexagonal polytypes is presented. Difference between the layers on the Si and C faces are discussed.

Abstract: The growth of homoepitaxial layers on off-oriented 6H-SiC substrates proceeds via step flow growth. Such epilayers can exhibit irregularities like step bunching, splicing or crossover of steps. The effects of the substrate off-orientation and growth temperature show an influence on formation of surface irregularities. The mean features seem to be given by the growth mode competition of two-dimensional growth to the step-flow growth.

Abstract: Homoepitaxial layers of fluorescent 4H-SiC were grown on 4 degree off-axis substrates by sublimation epitaxy. Luminescence in the green spectral range was obtained by co-doping with nitrogen and boron utilizing donor-acceptor pair luminescence. This concept opens possibilities to explore green light emitting diodes using a new materials platform.

Abstract: Fluorescent silicon carbide was grown using the fast sublimation growth process on low off-axis 6H-SiC substrates. In this case, the morphology of the epilayer and the incorporation of dopants are influenced by the Si/C ratio. Differently converted tantalum foils were introduced into the growth cell in order to change vapor phase stochiometry during the growth. Fluorescent SiC grown using fresh and fully converted tantalum foils contained morphological instabilities leading to lower room temperature photoluminescence intensity while an improved morphology and optical stability was achieved with partly converted tantalum foil. This work reflects the importance of considering the use of Ta foil in sublimation epitaxy regarding the morphological and optical stability in fluorescent silicon carbide.

Abstract: Bulk-like 3C-SiC was grown on 1.2 degrees low off-axis 6H-SiC substrates using a sublimation epitaxy technique. The effects of temperature ramp-up and increase in layer thickness on the 3C-SiC domain formation were explored. The temperature ramp-up had no significant effect on the domain size. The domain size was considerably increased and the crystal quality was significantly improved by increasing the thickness of the layer towards bulk-like material. Average full width at half maximum values of 149 arcsec and 65 arcsec were measured in samples with thicknesses of 305 µm and 1080 µm, respectively, at a footprint of 1x3 mm2. This result implies that heteropeitaxial growth of 3C-SiC on low off-axis 6H-SiC substrates by a sublimation method can be used to prepare 3C-SiC seeds or can be further developed for growth of bulk 3C-SiC material.