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1178-AA03-06

Silicon carbide nanowires grown on 4H-SiC substrates by chemical vapor deposition. Siva Kotamraju1, Bharat Krishnan1, Yaroslav Koshka1, Siddarth Sundaresan2, Hany Issa2, Ranbir Singh2. 1 2

Mississippi State University, Box 9571, Mississippi State, MS 39762, USA GeneSiC Semiconductor Inc., 43670 Trade Center Place, Suite 155 Dulles VA 20166, USA

ABSTRACT In this work, SiC nanowires (NWs) were grown by chemical vapor deposition (CVD) on commercial 4H-SiC substrates. The growth was conducted in an inductively heated hot wall CVD reactor traditionally used for homoepitaxy of 4H-SiC, operating at 150 Torr with H2 as the carrier gas. The growth experiments utilized the precursor chemistry that previously enabled the so-called low-temperature homoepitaxial growth of SiC – SiCl4 as the silicon precursor and CH3Cl as the carbon precursor. Vapor-liquid-solid (VLS) growth mode was employed. Two metal catalysts Au and Ni were used for NW growth in a wide range of growth temperatures from below 10500C to above 13000C. It was established that high precursor flow rates favor the regular epitaxial growth (though disturbed by the presence of the islands of the metal catalyst) at temperatures above 12000C. Reduction of the precursor flow rates and the growth temperature caused formation of micro-needles and eventually NWs. NW diameters in the range from below 10 to 100 nm were observed using scanning electron microscopy. Only SiC phase with no presence of Si, even for the growth temperatures down to 10500C, was confirmed by X-ray diffraction. INTRODUCTION Silicon carbide (SiC) offers rare opportunities for novel devices based on semiconductor nanowires (NWs). Unique properties of SiC include high breakdown field strength, thermal conductivity exceeding most of the existing materials, high saturation drift velocity, high radiation hardness, and high mechanical strength. These advantages stimulated the development of SiC devices for high power and high-temperature electronic applications, microwave devices, and high-temperature sensors [1,2]. In addition, the wide band gap of SiC makes it promising for optoelectronic devices operating through the visible spectrum into the ultraviolet. Finally, excellent physical and chemical stability and biocompatibility makes SiC devices very promising for biomedical applications [3,4]. Availability of different polytypes of SiC offers additional flexibility for developing devices based on SiC NWs. Different groups reported formation SiC NWs on variety of substrates including SiO2-covered Si, graphite, poly-SiC, etc [5,6,7]. In most of the reports, NWs were composed of cubic 3C-SiC polytype. Alternatively, the use of monocrystalline SiC substrates is interesting from the point of view of integrating SiC NWs with modern SiC devices as well as for exploring a possibility of polytype control in NW growth. In this work, growth of SiC NWs on commercial 4H-SiC substrates by chemical vapor deposition (CVD) is reported. The possibility of reproducing the substrate polytype was explored in ord