OD-XAS and EXAFS: Structure and Luminescence in Ge Quantum Dots

The source of visible luminescence from Ge nanocrystalline materials has been attributed to various phenomena such as the quantum confinement effect, surface contributions, and so on. In order to understand the origin of this light emission we have performed extended x-ray absorption fine structure (EXAFS) and optically-detected x-ray absorption spectroscopy (OD-XAS) using x-ray excited optical luminescence (XEOL) measurements on a range of Ge quantum dots prepared by various routes including stain etching, sol-gel method, and laser ablation. Such XEOL and OD-XAS studies on Ge and Ge-O rich regions allowed us to determine specificlocal sites responsible for PL.