CDTE CRYSTAL-GROWTH BY A SUBLIMATION TRAVELING HEATER METHOD

Both undoped and halogen-doped CdTe bulk crystals were grown in a monoellipsoid mirror furnace using a vapor zone transport method in closed ampoules (sublimation traveling heater method, STHM). Partial pressure gradients in the vapor affect the growth front stability and thus the maximum pulling rate significantly. A thermodynamic consideration leading to a ''critical'' growth rate J(crit) for sublimation growth of undoped CdTe in closed systems as well as a comparison with experimental results for halogen-doped material are introduced. In addition to chlorine, bromine and iodine were used as dopants for the first time in CdTe sublimation material. Resistivity measurements and photoluminescence 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) spectra of doped materials show a band within the defect region that may be assigned to a complex (V(Cd)2-; halogen(Te)+)-, the A-center previously found for Cl doping.