Surface Composition Changes and Ablation Dynamics in Excimer Laser Irradiated CdTe

Abstract

ABSTRACTWe have investigated the dynamics of KrF excimer laser ablation of CdTe and the fluence dependent changes in surface stoichiometry that accompany the laser ablation process. The composition of the CdTe surface was reversibly controlled between stoichiometric and a Te-rich condition by varying the laser fluence over the range from 15–65 mJ/cm2. The primary species ejected from the irradiated surface were Cd atoms and Te2 molecules. Their velocity distributions as measured by time-of-flight mass spectrometry were found to be Maxwellian. From the analysis of the velocity distributions, the preferential desorption of surface atoms, and the reversible nature of the process, we conclude that the desorption is due to a photo-thermal mechanism which mediates the competition between Te2 formation and desorption and the desorption of Cd atoms.