The influence of SiCl4s precursor on low temperature chloro carbon SiC epitaxy growth

Significant progress in reducing the growth temperature of the SiC epitaxial growth became possible in the previous work by using new chloro-carbon epitaxial growth method. However, it was established that even in the new process, homogenous nucleation of Si in the gas phase limited the growth rate. In the present work, new chlorinated silicon precursor SiCl4 was investigated as a replacement for the traditional silicon precursor SiH4 during the low-temperature chlorocarbon epitaxial growth. The new process completely eliminated the homogenous nucleation in the gas phase. Growth rate of 5-6 μm/h was achieved at 1300°C compared to less than 3 μm/h in the SiH4-based growth. The growth dependence on the C/Si ratio revealed that the transition from the C-supply-limited to the Si-supply-limited growth mode takes place at the value of the C/Si ratio much higher than unity, suggesting that certain carbon-containing species are favorably excluded from the surface reactions in the new process. Morphology degradation mechanisms, which are unique for the lowtemperature growth, were observed outside the established process window. Prior to this work, it remained unclear if CH3Cl simply served as a source of Cl to suppress homogeneous nucleation in the gas phase, or if it brought some other unknown improvements. In this work true benefits of CH3Cl in providing unique improvement mechanisms have been revealed. It was established that CH3Cl provided a much wider process window compared to C3H8. In contrast, even a very significant supply of extra Cl from a chlorinated silicon precursor or from HCl during the C3H8-based growth could not provide a similar benefit. The combination of the chloro-carbon and the chloro-silane precursors was also investigated at conventional growth temperature. High-quality thick epitaxial layers, with the growth rate up to 100μm/h were obtained, and the factors influencing the growth rate and morphology were investigated. Extensive optical and electrical characterization of the low-temperature and the regular-temperature epitaxial layers was conducted. The device-quality of the lowtemperature chloro-carbon epilayers was validated for the first time since the development of the chloro-carbon epitaxial process in the year 2005 by fabricating simple Schottky diodes and investigating their electrical characteristics