INP SINGLE-CRYSTAL GROWTH WITH CONTROLLED SUPERCOOLING DURING THE EARLY STAGE BY A MODIFIED LEC METHOD

A new liquid encapsulated Czochralski (LEC) technique for InP single crystal growth has been developed. In order to restrain the generation of twin bondaries from the shoulder of InP crystal by the LEC method, at the beginning of InP crystal growth, we tried to produce growth toward the lateral direction until reaching a 2-inch diameter without forming a cone angle (theta = 90-degrees) by controlling the optimum supercooling of the InP melt. As a result, it was found that although isotropic growth could restrain the twin boundary, anisotropic growth was likely to generate a twin boundary at the completion of lateral growth. After isotropic growth, InP single crystals were obtained reproducibly. That is, ten single crystal ingots of InP were obtained by this method. Furthermore, the etch pit density (EPD) of InP wafer with a 2-inch diameter was less than 2000 cm-2, except at the edge of the wafer, by Zn doping ((3.0-4.0) x 10(18) cm-3).