VERTICAL SEEDED MELT GROWTH OF GAAS

The growth of GaAs single crystals, 37, 50 and 62.5 mm in diameter, by the dynamic gradient freeze technique is described. Both quartz and pyrolitic boron nitride crucibles have been used successfully. Characterization of the crystals, 37 mm in diameter, grown in quartz is presented. Using very shallow temperature gradients over the melt and slow growth rates, the crystal-melt interface can be maintained flat over about 75% of the diameter. Through control of stoichiometry and with a thermal environment designed to reduce thermal stresses, about 50% of the crystals have a dislocation density of less than 1000 cm-2. Finally, we present the results from post-growth annealing. © 1990.