Regensburg 2013 – scientific programme

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DS: Fachverband Dünne Schichten

DS 9: Ion and Electron Beam Induced Processes

DS 9.3: Talk

Monday, March 11, 2013, 16:45–17:00, H8

The role of defect-types in ion beam induced stress in LiNbO₃ — •Emanuel Schmidt, Tobias Steinbach, and Werner Wesch — Institute of Solid State Physics, Friedrich Schiller University Jena

Ion-irradiation of complex crystalline materials, such as Lithium niobate (LiNbO₃), can result in the formation of different types of defects. With increasing ion-irradiation these defects accumulate or convert into more extensive defects, until in many materials a continuous amorphous surface layer is formed. This phase-transformation in general involves a density-change, which leads to the formation of mechanical forces. However, only a few quantitative studies on ion beam induced stress phenomena have been made, even though stresses in microstructures cause substrate bending, delamination and cracking as well as anomalous diffusion of dopands. To investigate the ion beam induced formation and relaxation of stress due to the formation and accumulation of defects and amorphous regions a scanning laser reflection technique was established at the FSU Jena. By means of this technique the bending of a freestanding sample away from the irradiated surface is defined by the compensation of forces and moments between the underlying substrate and the irradiated regions. In the case of LiNbO₃ these forces are highly anisotropic due to the crystal-structure of the material. The fluence dependent stress-evolution in LiNbO₃ shows a different behaviour compared to classical semiconductors, such as Ge and Si. The results are discussed in the framework of a defect-related model. Additional Rutherford-backscattering-measurements support the applied defect-relations in this approach.