The Incorporation Behavior of Co Impurities in a ZnSe Crystal

Abstract

This work is a study on the incorporation phenomena of cobalt magnetic ions in ZnSe. Zn1-xCoxSe (x < 0.02) polycrystals were prepared by the melt growth technique. The influences of Co impurities on the ZnSe crystal were investigated using x-ray diffractometry and Raman spectroscopy. The solid solubility of melt grown crystals is about x = 0.02(+/-0.0015). It was found that the lattice constant of the crystal increases linearly up to x = 0.0086 and then saturates as the amount of Co impurities increases. It is also observed that the To2 and LO1 Raman modes in Zn1-xCoxSe soften for x < 0.0086 by the addition of Co atoms. The oscillator strength, which is calculated using the energies Of the To2 and LO1 phonon modes, decreases as the cobalt content increases. There is a linear relationship between the ionicity and the oscillator strength with a slope of -7.02 x 10(25) S-2. From these observations, it is clear that the instability of the Zn1-xCoxSe crystal is mainly due to the ionicity difference between Zn and Co atoms.