Growth mechanism of 3C-SiC heteroepitaxial layer on Si substrates and its Schottky barrier characteristics

3C-SiC heteroepitaxial layers on Si substrates with atomically flat surfaces, which were never obtained by atmospheric pressure chemical vapor deposition (APCVD), were successfully grown by low pressure CVD (LPCVD). In order to clarify the reason why atomically flat surfaces can be obtained by LPCVD, we have studied the change of surface morphology on the early growth stage and the temperature dependence of the growth rates on APCVD and LPCVD epilayers, respectively. On the APCVD epilayers, the secondary nucleation occur and the growth rate does not depend on temperature. On the contrary, in the case of LPCVD, no secondary nucleation occurs and the growth rate depend on temperatures with an activation energy of 17.2 kcal/mol. Based on these results and consideration, the difference of principal species on the substrate between LPCVD and APCVD is discussed. We have also studied Schottky barrier characteristics of Au-3C-SiC diodes on LPCVD epilayers and good quality Schottky barrier junctions have been obtained. The reverse breakdown voltages were about 180 V. This value is two order of magnitude larger than those obtained for diodes on APCVD epilayers.