抄録
CdTe crystals doped with Zn were grown in Space Flyer Unit (SFU) by the process essentially based on the Bridgman technique. The growth apparatus was intended to realize the contactless growth of melt with growth ampule under microgravity environments. The sample, which has been grown in contact with the growth ampule during its liquid phase, contained many twin lamellae like usual CdTe grown on the ground. While, the sample which has been grown out of contact with the growth ampule during its liquid phase was single-crystalline (twin-free). This contrast suggests that the contact of melt with growth ampule is essential to cause twin lamellae in Cd Te. The single crystal is characterized by etch pit density (EPD) count, X-ray topography, photoluminescence (PL) and electron prove micro analyser (EPMA). The results show that the growth interface has changed from convex to concave along with growth direction. In accordance with the shape of growth interface, EPD increases from 2 x 104 cm- 2 to 2 X 105 cm- 2. The estimated value of the effective segregation coefficient for Zn is less than reported value because of the suppression of thermal convection in microgravity. Additionally, analysis of the crystal shape reveals that receding contact angle is close to 0 and solid-to-liquid density ratio is about 1.1 for CdTe.
