Bridgman growth of twin-free ZnSe single crystals

In order to grow a large twin-free ZnSe single crystal, we have adopted a c losed double-crucible to prevent the deviation from the stoichiometric comp ositions of the melt during Bridgman growth and determined the optimum grow th conditions. They contain a special temperature program, an over-heating temperature of 76 K from the melting point of 1797 K, and the temperature g radient at the growth interface of 30 K cm(-1) and a growth rate of 3.6 mm h(-1) determined in previous paper. Under these growth conditions. we have successfully grown twin-free high-quality ZnSe single crystals using a poly crystalline seed. Chemical etching on the cleaved (110) plane has shown tha t the average value of etch pit density (EPD) is about 2.0 x 10(5) cm (- 2) The rocking curves of 4-crystal X-ray diffraction have shown the 19 arcsec in full-width at half-maximum (FWHM). The photoluminescence (PL) spectra a t 4.2 K have shown the resolved intensive free exciton, bound exciton emiss ion lines and the weak DAP emission bands. The FWHM of I-l(d) emission was less than 0.5 meV. However, the deep-level emission bands were hardly obser ved. Above all, the results suggest that the ZnSe single crystals grown by the present method are of a very high quality. (C)1 2001 Elsevier Science B .V. All rights reserved.