EVOLUTION OF CADMIUM CHALCOGEN QUANTUM DOTS IN SILICATE-GLASSES

Semiconductor microstructures in glass have been studied using XAFS. T he local environments of Cd and Se have been followed during the devel opment of quantum dots in a potassium zinc silicate glass. Cd occupies both oxygen and chalcogen environments - the proportion of the latter increasing progressively with heat treatment. Se, on the other hand, is not coordinated to oxygen but to Se and to Cd. The proportion of Se -Se contacts decreases dramatically with the development of quantum do ts suggesting selenium clusters may provide the nucleating sites for C d chalcogen precipitates. The proportion of Se-Cd contacts increases w ith heat treatment, complementing the changes recorded in the Cd envir onment and enabling the optical absorption coefficients of the quantum dots to be calibrated.