Thermal conditions of growth and the necking evolution of Si,GaSb AND GaAs

The configuration of thermal gradient is illustrated for various types of crucible rotation, which is important for the creation of dislocations, which decreases along the grown axis of crystal. A new mechanism for dislocation elimination during the growth is proposed to explain this phenomenon, which provides a good agreement with the experimental results. The concentration of etch pits rapidly decreased from the beginning to the end of the crystals and the dislocation densities in the middle portion of all investigated crystals were found less than 102 cm^-2. The shallow vertical temperature gradients and virtually flat solidification interface prevented thermal stress from their building up in the crystals. As a result, the dislocation formation had random distribution. Using good necking procedures and choosing an appropriately oriented starting crystal with the shoulder angle <38.94° (assuming growth in <111> direction) it is possible to produce almost dislocation-free crystals without resorting to additional doping normally employed to reduce dislocation formation. This revised version was published online in July 2006 with corrections to the Cover Date.