Characterization of Bridgman-Grown Bulk Gallium Arsenide: Microscale Homogeneity

Undoped bulk crystals of gallium arsenide were grown by horizontal Bridgman methods. The effect of the temperature gradient impressed over the melt, and the influence of the melt composition, were systematically investigated. Dislocation etch-pits and the interface striation patterns were revealed with mixed-hydroxide and photo- enhanced chemical methods. The interface curvature and stability were found to be remarkably sensitive to the gradient impressed over the melt. Very flat interfaces could be generated with relatively small temperature gradients. Interface striation spacing, reflecting the convective flow in the melt, also showed strong sensitivity to the driving force impressed on the melt.