Surface Morphology of 6H-SiC on various a-plane using Si 2 Cl 6 +C 3 H 8 +H 2 by Chemical Vapor Deposition
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Surface Morphology of 6H-SiC on various a-plane using Si2Cl6+C3H8+H2 By Chemical Vapor Deposition Shigehiro Nishino, Yasuichi Masuda, Satoru Ohshima and Chacko Jacob Department of Electronics and Information Science, Kyoto Institute of Technology Matsugasaki, Sakyo, Kyoto 606-8585, Japan TEL : +81-75-724-7415, FAX : +81-75-724-7400 e-mail : [email protected], [email protected] ABSTRACT We have grown epitaxial layer introducing buffer layer using N2 doping on 6H-SiC (1120) and (1100) substrate. The improvement of morphology could be obtained for (1120) and (1100) epilayers. Morphologies of (1120) epilayers were independent on off-orientations, Morphologies of (1100) epilayers were very sensitive to the off-orientations. The quality of epilayer, and impurity incorporation for a-plane were very influenced by the surface treatment before CVD growth compared to (0001) epilayers. INTRODUCTION To realize the devices, it is important to know the morphological dependence of the epilayer on various orientations of the substrates [1,2]. Most of the SiC homoepitaxial growth is carried out on (0001) Si basal plane inclined several degrees off toward direction. Recently, epilayer on (1120) face of a-plane is also focused because high quality (1120) epilayer introducing buffer layer using N2 doing can be grown [2], and high channel mobility of MOSFET was achieved [3]. However, behavior of the buffer layer for surface morphology has not been known in detail. Additionally, off orientation dependence of morphologies for (1120) and (1100) of a-planes has not been studied. This work investigates the surface morphological effects introducing the buffer layer of 6H-SiC (1120) and (1100) epilayers using Si2Cl6+C3H8+H2 systems. To obtain further information about orientation effects, hemispherically polished substrates were used. The morphological orientation effects of epitaxial layer on 6H-SiC (1120) and (1100) hemispherical substrates were also investigated. The samples were characterized using optical microscopy, low temperature photoluminescence. EXPERIMENTAL Epitaxial growth was carried out by atmospheric-pressure CVD in a horizontal cold-wall reactor [4]. Source gases were Si2Cl6 (hexachlorodisilane) as Si source and C3H8 (5 % in H2) as C source with H2 carrier gas. The growth temperature was 1550ºC, the C/Si ratio was 10. The n-type 6H-SiC (1120) and (1100) substrates were home-made wafers made by our sublimation system [5]. The 6H (0001) Si-face inclined 3.5º off was placed side by side on an SiC-coated susceptor for comparison. The 6H hemispherical substrates were prepared on H2.10.1
(1120) and (1100) and commercial 6H-SiC substrates inclined 3.5º off from (0001) Si-face or (0001) C-face toward . The diameter of the hemispheres was 15 mm, and off angle was obtained at least 0º to 15º off for various directions. By using those substrates, morphological stability of the epilayer in various directions, , could be investigated. These growth parameters were optimized to obtain smooth surface of epilayers using 6H-SiC substr
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