GALLIUM ARSENIC SINGLE CRYSTAL INGOT, ITS PRODUCTION, AND GALLIUM ARSENIC SINGLE CRYSTAL WAFER USING THE SAME

摘要

PROBLEM TO BE SOLVED: To make the production of wafers suitable for the ion injection producible in a high yield by obtaining GaAs single crystal that has a low EL2 concentration and high uniformity from the top to the tail. SOLUTION: Seed crystal 3 of GaAs single crystal 3 is arranged in the lower part of the crucible 5 in the rack 8 and GaAs polycrystal is charged in the remaining space of the crucible 5 and the polycrystal are covered with B2 O3 as a sealant 4. Then, an inert gas is introduced into the air-tight vessel 10 and the pressure is adjusted to a prescribed value. The crucible is heated, with the heater 6 so that the temperature in the upper part may become more than 5 deg.C higher than the bottom temperature to melt the GaAs polycrystal. Then, the rack 8 is allowed to move downward with the lower shaft 19 to solidify the polycrystal melt 2 thereby growing a single crystal of GaAs. The resultant GaAs single crystal ingot has the EL concentration ranging of from 0.8 to 1.4×10<16> cm<-3> , the change rate of the EL2 concentration is <=10% at the top and the tail and the single crystal is homogeneous.