The mobility of beta-SiC thin films grown on (100) Si substrates by low-pressure rapid thermal chemical vapor deposition (LP-RTCVD) has been found to have a 200% improvement over that prepared by conventional low-pressure CVD. The SiC growth is achieved using a C3H8-SiH4-H-2 reaction gas system at a reduced pressure of 2.5 Torr. Both X-ray and transmission electron microscopy patterns show that the grown layer is single-crystal beta-SiC. The influence of the growth conditions on the electrical properties of the SiC layer was also investigated. It was found that the maximum electron mobility can reach 254 cm(2) V-1 s(-1) for carrier concentrations of ( 1-4) x 10(17) cm- (3) and at substrate temperature of 1150 degrees C. The electron mobility is the highest one reported to date for the low-pressure heteroepitaxial SiC films on Si substrates.