Bridgman growth of twin-free ZnSe single crystals

Abstract

In order to grow a large twin-free ZnSe single crystal, we have adopted a closed double-crucible to prevent the deviation from the stoichiometric compositions of the melt during Bridgman growth and determined the optimum growth conditions. They contain a special temperature program, an over-heating temperature of 76 K from the melting point of 1797 K, and the temperature gradient 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 polycrystalline seed. Chemical etching on the cleaved (110) plane has shown that the average value of etch pit density (EPD) is about 2.0×10 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 at 4.2 K have shown the resolved intensive free exciton, bound exciton emission lines and the weak DAP emission bands. The FWHM of I 1 d emission was less than 0.5 meV. However, the deep-level emission bands were hardly observed. Above all, the results suggest that the ZnSe single crystals grown by the present method are of a very high quality.