Growth of high-purity ZnTe single crystals by the sublimation travelling heater method

A travelling heater method (THM) was developed to grow high-purity ZnTe from the vapor phase. This crystal growth method is called the “sublimation THM”. The temperature of the sublimation interface was set at 815°C and the temperature of the growth interface was varied from 785 to 800°C. The growth rate was 3 mm/day. Under these conditions, it was found that the growth process was mainly due to surface nucleation. Characteristics of the crystals were compared with those of solution-THM and vapor phase epitaxially grown crystals. The free-exciton line at 2.381 eV strongly appears and a doublet structure in neutral- acceptor bound exciton at 2.375 eV is clearly resolved with splitting energy of about 0.7 meV. We thus conclude that the THM from the vapor phase is suitable for preparing ZnTe single crystals which have excellent luminescent properties.