Etch pit study of ZnSe single crystal grown by the iodine transport method

Abstract

The etch pit distribution of a ZnSe single crystal grown by the iodine transport method was studied. The measurement was made along the direction from the seed part to the tail of the crystal and the etch pit density (EPD) is distributed between 3 x 10 3 and 5 x 10 4 cm -2. The distribution of the EPD was uneven on the crystal, which was probably due to the thermal stress which was introduced during the cooling process. The concentration of iodine atoms which are doped during crystal growth was estimated by secondary ion mass spectroscopy (SIMS). The iodine concentration is almost uniform in the crystal within the sensitivity of the SIMS, and it has no correlation with the number of etch pits in the measurement area. A double crystal X-ray diffraction measurement indicates a good correlation between the EPD and the full width at half maximum (FWHM) of the X-ray rocking curve; the narrowest FWHM of the (333) diffraction was 6.2 arc sec, which is very close to the ideal value of 4.2 arc sec.