The structure of CdTe, CdMnTe, CdZnTe single crystals obtained from the melt at different formation conditions of nucleation center is investigated. For growing of large single crystal by Bridgman method form of the bottom of an ampoule, where crystals growth begins, is very important. For crystals less than 20 mm in diameter the best single crystals reproducibility is observed if ampoules with the system of neckings is used, for crystals of 20-30 mm in diameter - at the use of ampoules with a cone bottom. For crystals of 30-60 mm in diameter the best results gives the use of flat bottom with light conductor or heat conductor. Interesting results were obtained at the use of ampoules with a flat bottom, light conductor on the center and with double walls. A gap between walls was filled by the CdTe melt. This melt crystallized earlier, than the melt which in the internal ampoule. The released heat of crystallization heated the internal walls of the ampoule and aligned crystallization front. The temperature conditions of this process were studied theoretically.