GROWTH OF HIGH QUALITY SEMICONDUCTORS BY CONTAINER LESS METHOD UNDER MICROGRAVITY

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The present studies were carried out as an international joint research among Japan, U.S.A., China and Germany. At first, undoped GaSb, Te doped GaSb and (Ga, Al) Sb were grown on ground by vertical Bridgman method. It was found that a great reduction of dislocation density in undoped GaSb was achieved by pre-growth annealing of GaSb melt. Then, Te doped GaSb which has been grown by Czochralski method was melted in the vertical Bridgman furnace from one end and regrowth was conducted employing un-melted part as a seed. It turned out on ground there was strong convection which introduces impurity Striations and makes the melt completely mix. (Ga, Al) Sb was successfully grown by vertical Bridgman method. (Ga, Al) Sb is suitable to study the elementary process of impurity doping taking Al as an impurity the thermodynamical properties of which has been well known.Te doped GaSb grown in space by Chinese recoverable satellite has been investigated by X-ray topograph and X-ray 3-crystal diffractometry (TCD). It was found that dislocation density is greatly reduced where the growth was conducted contact free. In the part of the contact free growth, the presence of precipitates was observed. It was suggested that the precipitates were probably composed of Te which was relatively highly doped. TCD also showed the quality of the crystal grown under contact free condition was very high. In US side, Detached solidification with model materials were conducted and the detached growth under microgravity was reviewed.