Homogeneous In0.3Ga0.7As crystal growth by the traveling liquidus-zone method

We have succeeded in growing compositionally homogeneous In0.3Ga0.7As singl e crystals by a newly developed growth method, the traveling liquidus-zone method. In this method, a narrow liquidus-zone saturated by a solute is for med under a relatively low temperature gradient. Since the solubility depen ds on temperature, solute concentration gradient at the freezing interface is established. The concentration gradient causes diffusion of the solute t owards a low concentration side. At the freezing interface, crystal growth proceeds due to the decrease of solute, while solute concentration increase s at the opposite side of the zone and part of the remaining feed is dissol ved. Thus, the zone travels under the temperature gradient spontaneously. W hen we translate the sample in accordance with this spontaneous zone travel ing rate, solute concentration and temperature at the freezing interface ar t: kept constant and long homogeneous mixed crystals can be grown. The expe rimentally determined appropriate sample translation rate was about 0.25 mm /h at a temperature gradient of 20 degreesC/cm. Homogeneous crystals longer than 30 mm were obtained. Although 15-20 mm long single crystals were obta ined for diameters ranging fi om 1.6 to 2.0 mm, polycrystallization occurre d for larger diameter crystals such as d = 14.5 mm. (C) 2001 Elsevier Scien ce B.V. All rights reserved.