High quality 4H-SiC monocrystalline him were homoepitaxially grown on 8.0 degrees off-oriented (0001) 4H-SiC at a low temperature (1643 K) by metal-organic chemical vapor deposition (MOCVD). The correlation between the structural properties of the films and the growth parameters, in particular, the substrate temperature, and the flow rate of source material BTMSM, was investigated to elucidate the possible benefits of a single precursor on low-temperature thin film growth. The films were examined by optical microscopy, scanning electron microscopy (SEM), triple crystal X-ray diffractometry (TCD), and photoluminescence. Reciprocal space mapping results of the (0004) Bragg spot showed that the full width at half maximum (FWHM) of the rocking curve of the epilayer grown at 1643 K was 9.3 arcsec, which is extremely low as compared with the lowest value reported (13 arcsec). The high film quality was confirmed by low-temperature photoluminescence. The homoepitaxial growth condition for high quality monocrystalline 4H-SiC was also suggested in terms of the growth temperature and supersaturation of the source material.