In papers [1,2] the possibility of novel Axial Heat flux close to the Phase interface crystal growth method (AHP method) was analyzed by numerical simulation to find conditions for obtaining Zn uniform distribution in CZT. These results was used and  as a results a uniform Zn distribution for all volume of CZT 2 inch ingot was obtained. Crystals of CZT were grown under high pressure of Ar without using seed. But for high-pressure (HP) AHP crystal growth there is some evaporation of Cd,  the melt is concentrated by Te and the temperature of crystallization is decreased. So, morphological instability of the melt-crystal (m/c) interface can occur,  it results in micro inclusions of Te. To grow CZT crystal without micro inclusions the area of morphological stability of the m/c interface was found for AHP CdZnTe crystal growth.

A set of AHP crystal growth experiments were conducted at different values of temperature gradient and crystal growth rate to find the area of morphological stability. CZT ingots were grown in 2 and 3 inches graphite crucibles using the AHP baffle as shown in Fig. 1. The thermocouples T₁ - T₄ were used to calculate axial temperature gradient in the melt, gradT_m. The values of gradT_m were in the range of 5 – 60 K/cm. The accuracy of control of temperature was within 0.05 – 0.1 K. For obtaining a large value of gradTm the crystals were grown with a small distance between bottom of the AHP baffle and a melt/crystal (m/c) interface). Crystal growth rate V was in the range of 1 – 20 mm/hour.

The grown crystals were cut along the longitudinal direction and position of the m/c interface found where morphological instability took place. The crystal growth rates and values of gradT_m were calculated for these m/c interface positions using a one dimensional heat transfer model, values of temperature T1 and T3, T4 and their temporary dependence. Thus, the set of data Vi and gradT_mi were found which resulted in the morphological instability. The obtained data is presented in Fig. 2.

1. A. Yeckel, J. J. Derby, J. of Electronic Materials, Vol. 33, No. 6 (2004) 1-12.

2. M. Marchenko, V. Golyshev, S. Bykova, J. of Crystal Growth 303 (2007) 193–198.

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