THE EFFECT OF VERTICAL VIBRATION OF THE AMPOULE ON THE DIRECTIONAL SOLIDIFICATION OF INSB-GASB ALLOY

The effects of vertical vibration of the ampoule on the directional so lidification of InSb-GaSb alloy in the vertical Bridgman-Stockbarger c onfiguration were investigated. The microstructure and compositional p rofile of In0.2Ga0.8Sb grown with and without vibration were studied. The axial composition profile with and without vibration corresponded to complete mixing of the melt. No significant radial composition vari ations were observed. Though twins were slightly increased by the appl ication of vibration, the number of grain boundaries in the ingots gro wn with vibration was less than in ingots grown without vibration, esp ecially in the first-to-freeze parts. With the application of vertical vibration with 20 Hz frequency/0.5 mm amplitude to the growth ampoule , the ingots had the fewest grain boundaries. Vibration did not change the interface shape significantly during the first part of the ingots . However, the interface became more concave during the last part of t he solidification when vibration was applied. Twinning mostly initiate d from the edge of the ingot where they contacted with the ampoule wal l.