Study of SiC single-crystal sublimation growth conditions

Abstract

The development of silicon carbide microelectronics depends on the availability of high quality substrates. Nowadays, the most satisfactory technique for growing SiC single crystals is sublimation growth. In this paper, conditions for the sublimation growth of SiC are studied. Growth of crystals was carried out using a hot wall reactor. Acheson platelets were used as seeds and the source material was an abrasive silicon carbide powder. The temperature of source powder and substrate varied from 2150 °C to 2250 °C and 2000 °C to 2150 °C respectively. The growth chamber, a 90 mm diameter graphite crucible, was heated by r.f. induction. The thermal gradient was set by coil position. Crystal quality was investigated by X-ray diffractometry, optical microscopy, photoluminescence, and Raman spectroscopy. Growth rates from 0.1 to 2 mm h −1 were obtained. Typical features of the grown crystals are 6H-SiC, rocking curve peaks with full width at half-maximum of 30 s, n-type crystals, n = 10 17 cm −3 as measured by mercury probe. This work enabled us to establish limits for SiC growth conditions. Evolution of the single-crystal growth rate was investigated with temperature variation but also with variation in the silicon of the source powder. The crystal quality was examined and related to growth conditions.