PREPARATION OF GROUP III-V COMPOUND SEMICONDUCTOR SINGLE CRYSTAL

摘要

PURPOSE:To obtain group III-V compound semiconductor single crystal of high quality by performing shape control using an angle of a shoulder part of a crystal in the direction of the crystal axis as a referential signal to form the shape of the crystal to a desired value in the course of crystal growth. CONSTITUTION:The weight and the pulling speed of a seed crystal are measured with a weight sensor 8 and a position sensor 9 as soon as the pulling of seed crystal is commenced. Both measured values are inputted continuously into an operation circuit 10, and the angle of the shoulder part of the crystal to be formed in accordance with the rate of increase of the crystal dia. is operated. The value of the angle is compared with the previously set shoulder angle, and a temp. compensation value signal corresponding to the difference of both shoulder angle values is inputted to a heat temp. adjustment circuit 11 and the temp. of the heater is adjusted so as to bring the angle of the crystal in the course of crystal growth to near the set value. By this method, a shoulder part having a smooth shape is formed and a semiconductor single crystal with a small dislocation distribution and superior characteristic is obtd.