Papers by Author: Ryo Tanaka

Abstract: Solution growth was performed using a free-standing (001) 3C-SiC epilayer as a seed crystal at a growth temperature of 1700°C. The seed crystal was prepared by a CVD method on the undulated Si substrate. 3C-SiC stably grew on the (001) seed crystal. However, dark stripes from the seed crystal to the grown crystal along {111} planes were clearly observed. The stripes were due to the high-density stacking faults extended from the stacking faults in the 3C-SiC epilayer that were induced during the CVD growth on Si substrate.

Abstract: We investigated the effects of the solution growth process on the polytype and crystal quality of the crystals grown on (111) 3C-SiC seed crystals. In spite of the use of 3C-SiC seed crystals, the polytype of the grown crystal changed from 3C-SiC to 6H-SiC, because the stacking errors easily occur due to the similarity of the (111) face of 3C-SiC and the (0001) face of 6H-SiC. Moreover, the grown 6H-SiC crystal affected the crystal quality of the seed crystal, i.e., high-density stacking faults were induced in the seed crystal after the growth process.

Abstract: A solution growth of 3C-SiC was performed on (111)Si-face or )111(C-face of 3C-SiC seed crystal at around 1700 °C by dipping method. The polytype of the crystal grown on the Si-face immediately changed to 6H-SiC. On the other hand, 3C-SiC stably grew on the C-face except for a small number of 6H-SiC precipitates. The polytype transition phenomenon can be explained by the difference of the chemical potential and the solution-crystal interfacial energy between 3C-SiC and 6H-SiC. To grow a larger 3C-SiC crystal, we carried out a long-term growth for 30 hours on the C-face. In the first 10 hours, the polytype of the grown crystal was 3C-SiC. In the next 10 hours, however, the polytype changed from 3C-SiC to 6H-SiC. According to our studies, 6H-SiC tends to grow on 6H-SiC at around 1700 °C, while both of 3C-SiC and 6H-SiC can grow on 3C-SiC at around the same temperature. In this case, 6H-SiC grows on 6H-SiC precipitates and then the dominant polytype changes to 6H-SiC after several 6H-SiC precipitations. To grow 3C-SiC crystal stably, it is necessary to surpress completely the polytype transition by the growth on C-face at lower growth temperatures.

Abstract: We investigated effects of Ti and Ge additions to Si solvent on the volume and the polytype of SiC precipitate in unseeded SiC solution growth. The Ti addition increased the amount of SiC precipitates. Compared to pure Si solvent, the amount of crystal grown in Si-30at%Ti at 1600 °C increased by 5 times. In addition, the Ti addition induced the precipitation of 6H-SiC. Further, the Ge addition to Si-Ti solvent promoted several polytype precipitations (4H and 6H). These results indicate the possibility of polytype control by solvent composition.