Fabrication of SiGe bulk crystals with uniform composition as substrates for Si-based heterostructures

SiGe bulk crystal was grown by the multicomponent zone-melting method equipped with an in situ monitoring system of the position and the temperature at the crystal-solution interface. By utilizing the in situ monitoring system, an attempt was made to control the interface position at a fixed position during growth by balancing the growth rate and the pulling rate of the crystal. This led to realization of SiGe bulk crystal with Ge composition of 0.86±0.004 over 22 mm in length. However, as growth proceeds, development of small angle boundaries was evidenced by X-ray characterizations. This polycrystallization was found to be accompanied with appearance of deep-level emission in photoluminescence spectra. A preliminary result to grow SiGe with intermediate composition, which is important for Si-based heterostructures, was also performed.