Yoichiro Tarui

Heteroepitaxial growth of single crystalline 3C‐SiC on Si substrates by gas source molecular beam epitaxy

Heteroepitaxial growth of 3C‐SiC on Si substrates by gas source molecular beam epitaxy was investigated. Both Si(001) and Si(111) surfaces were carbonized using a C2H2 gas molecular beam to convert the surface region into single crystalline 3C‐SiC prior to crystal growth. The supply of C2H2 was started at 400 °C, and the substrate temperature was raised at a rate of 7 °C/min. An amorphous‐like layer was observed at 870 °C. Raising the temperature at a rate of 2 °C/min from 870 to 970 °C, a single crystalline 3C‐SiC layer was obtained. In the case of Si(001), increase of C2H2 supply resulted in improvement of crystallinity, because of a thin (∼50 A) 3C‐SiC layer formed at an early stage of carbonization, which prevented outdiffusion of Si atoms. The thickness of the 3C‐SiC layer did not increase for prolonged time of carbonization after formation of the thin layer. In the case of Si(111), the increase of C2H2 supply resulted in a thicker layer of 3C‐SiC with a rough surface, because the channels of Si outd...

Low-temperature heteroepitaxial growth of cubic SiC on Si using hydrocarbon radicals by gas source molecular beam epitaxy

Abstract Single-crystalline cubic SiC on Si in gas source molecular beam epitaxy was achieved by a combination of carbonization of a Si surface and subsequent crystal growth using hydrocarbon radicals and Si 2 H 6 . A carbonized layer with a smooth surface was obtained at 750°C. The thickness of the carbonized layer was found to be controlled easily by the number of methyl radicals. In 3C-SiC homoepitaxial growth at 1000°C on a carbonized layer, the Si 2 H 6 flow rate affected the surface morphology of the 3C-SiC epitaxial layer. At a typical flow rate of methyl radicals, the growth rate was kept constant, regardless of the Si 2 H 6 flow rate, which implies a layer-by-layer growth mode.

Cracking of Saturated Hydrocarbon Gas Molecular Beam for Carbonization of Si(001) Surface

Carbonization of Si(001) surfaces by saturated hydrocarbon gas molecular beams in a high vacuum was carried out employing a thermal cracking technique. In the case of C3H8 and C2H6, the Si surfaces were carbonized at 750°C with a cracking temperature of 1300°C, and 3C-SiC layers were obtained. Decomposition of C3H8 by cracking was observed in quadrupole mass analyzer (QMA) measurements. In the case of C2H6, the effect of cracking was less obvious, and decomposed species were not observed except for H2 in QMA measurements. In the case of CH4, no effect of cracking was observed. This result seems to be related to the difference in the bond strengths of molecules.

Controlled carbonization of Si(001) surface using hydrocarbon radicals in ultrahigh vacuum

Abstract Carbonization of a Si(001) surface by hydrocarbon radicals is obtained in an ultrahigh vacuum at 750°C. Hydrocarbon gases such as C 3 H 8 , C 2 H 6 and CH 4 are decomposed by thermal cracking, and generated radical species are investigated by quadrupole mass analysis. The thickness of carbonized layer is controlled easily by cracking temperature and exposure time, and very smooth surfaces are obtained. The differences in the cases of various hydrocarbon sources are discussed in detail.

Specular Surface Morphology of Aluminum-Implanted 4H-SiC(0001) by SiH4-Added Ar Anneal

Surface morphologies of aluminum-implanted 4H-SiC(000) after a high-temperature anneal have been investigated in comparison with those of 4H-SiC(0001). The high-temperature anneal above 1450°C in pure Ar at 25000 Pa has been found to result in extreme roughness, which is not seen for 4H-SiC(0001). By the SiH4-added Ar anneal at 1500°C, a remarkably flat surface and an electrical activation rate of more than 90% are attained.

Initial Stage of Heteroepitaxial Growth of SiC on Si by Gas Source MBE Using Hydrocarbon Radicals

Heteroepitaxial growth of 3C-SiC on Si in gas source molecular beam epitaxy ( GSMBE ) was carried out by a combination of carbonization of a Si surface and subsequent crystal growth on it using hydrocarbon radicals and Si 2 H 6 . The carbonization process and the initial stage of the subsequent growth during the intermittent supply of Si 2 H 6 have been studied by a reflection high-energy electron diffraction (RHEED) observation. A Si surface was chemically converted to 3C-SiC at 750°C, and homoepitaxial growth on the carbonized layer could be obtained at 1000°C. Si atoms generated by thermal decomposition on a surface would react with hydrocarbon radicals, forming SiC through a layer by layer growth mode.