Deformation of amorphous silicon nanostructures subjected to monotonic and cyclic loading

摘要

An atomic force microscope (AFM) was used to characterize the deformation behavior of amorphous Si (a-Si) nanostructures subjected to monotonic and cyclic loading. The sample geometry was specially designed (in the form of elbow) using finite element modeling for the purpose of these tests, and the samples were grown by glancing angle deposition. When deformed monotonically at room temperature, the a-Si specimens exhibited a nonlinear force-displacement response at forces larger than a critical force, a phenomenon not observed in bulk silicon. A fatigue testing methodology based on the use of the AFM was established. The fatigue life of the a-Si specimens was observed to increase by five orders of magnitude with a 50% reduction in the applied force amplitude. It was verified that this delayed failure is caused by progressive damage accumulation during cyclic loading. These results are compared with literature data obtained from micron-size specimens.