Homogenization of zinc distribution in vertical Bridgman grown Cd0.96Zn0.04Te crystals

One of the most pressing issues in the growth of high quality single crysta l Cd0.96Zn0.04Te material, is to achieve homogenization of the high axial v ariation of Zn concentration, caused by the larger than unity segregation c oefficient of Zn in CdTe. This is achieved in our crystals (i) by thermal a nnealing of the CdZnTe crystal, which redistributes the as grown Zn distrib ution by solid state diffusion of Zn (this solid state diffusion of Zn occu rs at three stages (a) during the growth when the solidified crystal is nea r to the melting point temperature, (b) during the post growth annealing of the crystal at a high temperature and (c) during the cooldown to room temp erature) and (ii) by the reduction of Zn segregation during the growth stag e by enhanced convective mixing of the melt, through a proper choice of amp oule and furnace dimensions. By adopting suitable growth parameters and suf ficient post growth annealing it has been possible to grow Cd0.96Zn0.04Te c rystals, which have nearly 75% of their fraction within 1% Zn concentration variation.