Temperature Dependent Internal Friction Behavior of Single Crystal Germanium Studied by the Impulse Excitation Technique
More and more, single crystal germanium and silicon layers and substrates are used together to process advanced nano-eletronic devices. The thermal stresses during crystal growth and device processing have an important impact on generation and diffusion of point defects and in the worst case also can lead to dislocation generation. Although the temperature dependent mechanical properties of silicon are well known, this is much less the case for germanium.
In the present study, the impulse excitation technique was used to analyze the temperature dependence of the internal friction in single crystal Ge in the <111>, <100> and <110> directions between room and melting temperatures. A similar set-up was used as in  but equipped with a specimen chamber and specimen suspension system allowing heating the samples in an inert atmosphere up to the Ge melt temperature. Between room temperature and melt temperature, three internal friction peaks were observed for each crystallographic orientation after internal friction spectrum analysis, a typical spectrum is shown in the figure. The mechanism leading to these peaks is thermally activated. To interpret the observed internal friction peaks, various aspects such as activation energy of peaks, peak positions and relaxation time will be discussed. The origin of the relaxation peaks is associated with intrinsic point defect processes and/or extended defect formation.
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