Surface trace element characterization of synthetic single crystal Al2O3 at the SSRL

Detailed surface trace impurity element analyses (Ti, Cr, Fe, Co, Ni, Cu, and Zn) have been performed on synthetic sapphire grown by the HEMTM technique. Both bulk and surface measurements, yielding information on the spatial distribution of the elements are needed as part of our effort to obtain correlations between optical absorption at 1064 nm and trace element concentrations. Transition metal elements (e.g. Ti, Cr, and Fe) are known to produce absorption in sapphire and therefore were the focus of our study. We report results from our use of total reflection x-ray fluorescence (TXRF) to determine trace transition elements on the surface of synthetic sapphire. The measurements show concentrations for Cr at 109 atoms/cm2 to Fe at 1012 atoms/cm2 and are consistent with bulk trace element studies done using instrumental neutron activation analysis (INAA).