Advances in LEC (Liquid-Encapsulated Czochralski) Growth of InP Crystals

摘要

By reducing the temperature gradients in the vicinity of the crystal-metal interface, 35-mm-diameter InP boules with much reduced dislocation densities have been grown by the liquid-encapsulated Czochralski technique. A reduction in the residual donor concentration of InP grown by this technique has been achieved by using In-rich charges prepared by adding elemental In to polycrystalline InP ingot material. Nominally undoped crystals with carrier concentrations as low as 1-2 x 10 to the 15th power/cc and 77 K mobilities as high as 70,000/sq cm/v/s have been obtained. By growing doped crystals at increased seed or crucible rotation rates, short-range longitudinal variations in dopant concentration have been reduced to a few per cent, as determined by optical absorption measurements with a scanning CO2 laser.