Internal friction in intrinsic and n-type germanium and silicon

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Abstract
The dependence of the high‐temperature internal friction of germanium and silicon, both intrinsic and highly n type, was measured as a function of temperature, frequency, dislocation density, and dopant concentration. An acoustoelectric peak in both germanium and silicon was detected and found to agree well with the theory of Weinreich. The high‐temperature dislocation‐dependent damping in intrinsic germanium and silicon was studied and seen to be consistent with most previous studies. If deformed at high temperature and allowed to anneal, highly doped n‐type material behaved intrinsically due to preferential precipitation at dislocations; however, if deformed at moderate temperatures and not allowed to anneal, such crystals exhibited a greatly enhanced dislocation‐dependent internal friction which depended on the extrinsic carrier concentration. A theory was developed for dislocation damping in semiconductors and was found to agree well with experimental results. The model is based upon electronic viscous damping of dislocations by excess current carriers whose lifetimes are controlled by Auger recombination processes.