CDTE CRYSTAL-GROWTH BY A SUBLIMATION TRAVELING HEATER METHOD

Both undoped and halogen-doped CdTe bulk crystals were grown in a mono ellipsoid mirror furnace using a vapor zone transport method in closed ampoules (sublimation traveling heater method, STHM). Partial pressur e gradients in the vapor affect the growth front stability and thus th e maximum pulling rate significantly. A thermodynamic consideration le ading to a ''critical'' growth rate J(crit) for sublimation growth of undoped CdTe in closed systems as well as a comparison with experiment al results for halogen-doped material are introduced. In addition to c hlorine, bromine and iodine were used as dopants for the first time in CdTe sublimation material. Resistivity measurements and photoluminesc ence investigations were performed. Resistivities in the range of 1.2 x 10(6) to 8 x 10(8) OMEGA cm were found; the photoluminescence (PL) s pectra of doped materials show a band within the defect region that ma y be assigned to a complex (V(Cd)2-; halogen(Te)+)-, the A-center prev iously found for Cl doping.