Properties of Heteroepitaxial 3C-SiC Layer on Si Using Si 2 (CH 3) 6 by CVD
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ABSTRACT Single crystal cubic silicon carbide ( 3C-SiC ) has been deposited on Si(100) by atmospheric CVD at 13500C using Si2(CH3)6. The 3C-SiC epilayers were characterized by XRD, Raman scattering and photoluminescence (PL). The 3C-SiC distinct TO near 796 cm- 1 and LO near 973 cm- 1 were recorded by Raman measurement. The PL spectra of SiC films at 11K included the nitrogen-bound exciton (N-BE) lines, the "defect-related" W band near 2.15eV, and 2.13eV peak corresponding to D-A pair recombination as well as the "divacancy-related" D 1 peak at 1.97eV. The thickness dependences of Raman and PL measurement were made and it was observed that tensile stress and strain in films decrease with increasing film thickness. Electrical properties of the films were measured by making schottky diodes and using Van der Pauw method. Above 300K, the electron mobility changed as J.-H - T -1.45 - -1.56 and the highest mobility was about 400 cm 2 V-ls- 1 at room temperature. In 3C-SiC the scattering processes are affected prominently by acoustic scattering in this temperature range.
INTRODUCTION The heteroepitaxial growth of 3C-SiC on Si substrates by CVD method has been investigated intensively. This is because commercially available 6H and 4H-SiC wafers still have
some problems such as small substrate size and defects like micro-pipes. Atmospheric pressure CVD (APCVD) method has been widely used for the growth of 3C-SiC on Si substrate. It has been reported that SiC films can be grown on Si substrate at a relatively low temperature in APCVD system by pyrolyzing HMDS (hexamethyldisilane: Si2(CH3)6), a single-source organosilane precursor which contains direct Si-C bonds. Most of the work on the growth of SiC
films using HMDS reported SiC film thickness of about 51im on Si(lll) substrate[1, 2]. However, because the thermal stress in the films on Si(l 11) is larger than that of Si(100), a number of microcracks exit easily in 3C-SiC films on Si( 111)[3]. It is clear that using a (100) Si
substrate instead of a (111) Si substrate will reduce thermal stress. A higher quality crystallinity 3C-SiC films can be obtained on Si(100). In this work, we report the growth of high quality single crystalline 3C-SiC films on Si(100) up to 17.51am using Si2(CH3)6 + H2 gases by APCVD. The resulting film surfaces are all mirror-like. The growth rate of 3C-SiC films was about 4.3Wn/h. This growth rate is rather high compared with SiH4 + C3H8 system. The 3C:SiC epilayers were characterized by XRD, Raman scattering and PL. We successfully obtained high quality single crystal 3C-SiC films and observed the complete line structure of PL at 11K. Thickness dependences of the Raman and PL measurement were determined and stress-related peaks were obtained. Electrical properties of 191
Mat. Res. Soc. Symp. Proc. Vol. 572 © 1999 Materials Research Society
the films were also measured by making Schottky diode and using the Van der Pauw method.
EXPERIMENTAL The CVD system used in this study was made from a 50mm diameter air-cooled horizontal quartz tube conn
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