Abstract
The nucleation and bulk growth of polycrystalline SiC in a 2 inch PVT setup using isostatic and pyrolytic graphite as substrates was studied. Textured nucleation occurs under near-thermal equilibrium conditions at the initial growth stage with hexagonal platelet shaped crystallites of 4H, 6H and 15R polytypes. It is found that pyrolytic graphite results in enhanced texturing of the nucleating gas species. Reducing the pressure leads to growth of the crystallites until a closed polycrystalline SiC layer containing voids with a rough surface is developed. Bulk growth was conducted at 35 mbar Ar pressure at 2250°C in diffusion limited mass transport regime generating a convex shaped growth form of the solid-gas interface leading to lateral expansion of virtually [001] oriented crystallites. Growth at 2350°C led to the stabilization of 6H polytypic grains. The micropipe density in the bulk strongly depends on the substrate used.
Highlights
Fluorescent silicon carbide (f-SiC) is a promising candidate in the field of optoelectronics for the fabrication of a novel monolithic all-semiconductor white LED structure [1]
In the case of fluorescent SiC, the research is very new and donor-acceptor co-doped sources are necessary. As no such materials exist we have previously reported on polycrystalline nitrogen and boron doped bulk SiC crystals grown using the physical vapour transport (PVT) technique [3]
In this work we investigate the growth of SiC crystallites on isostatically pressed highly purified and hereon deposited pyrolytic graphite substrates at the initial stages of growth of polycrystalline bulk SiC source material, i.e. when diffusion limited mass transport is activated due to the decrease of the environmental argon system pressure
Summary
Fluorescent silicon carbide (f-SiC) is a promising candidate in the field of optoelectronics for the fabrication of a novel monolithic all-semiconductor white LED structure [1]. In this work we investigate the growth of SiC crystallites on isostatically pressed highly purified and hereon deposited pyrolytic graphite substrates at the initial stages of growth of polycrystalline bulk SiC source material, i.e. when diffusion limited mass transport is activated due to the decrease of the environmental argon system pressure.
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