Investigation of interstitial Zn concentrations in additively colored ZnO using the uni-directional channeling and blocking technique

A new experimental technique which combines the channeling and blocking phenomena of energetic ions in single crystals has been utilized to investigate the concentration of Zn interstitials in additively colored ZnO single crystals. This method, called the uni-directional channeling and blocking technique, is directly sensitive to Zn interstitials and is useful in determining not only the concentration of such defects but their lattice position as well. Our measurements showed no evidence of Zn interstitials along either the Z or X axial directions of the additively colored crystals in concentrations ≥ 6 × 10¹⁸ interstitials/cm³. This limit is two orders of magnitude less than the concentrations reported by Mohanty and Azároff from measurements of the X-ray diffraction intensities for colored and uncolored ZnO crystals. They reported interstitial concentrations along the Z-axis direction of the additively colored ZnO of 1·6-6 × 10²⁰ interstitials/cm³. The implications of our measurements are discussed and compared to related results.