Stiff thin layers on compliant substrates can generate various surface structures using equi-biaxial stress caused by large thermal expansion rate differences. We investigated the detailed understanding on the evolution of self-assembled wrinkle patterns of ultra-thin amorphous silicon (a-Si) layers on polydimethylsiloxane substrate. It turns out that the generation of various wrinkle patterns depends on the position of their orientation, film thicknesses, mechanical properties of the a-Si films, and the amount of pre-strain. The various self-assembled patterns include one-dimensional wavy patterns, randomly ordered two-dimensional structured patterns, and herringbone structures. The self-assembled wrinkles can be characterized by the wavelength and amplitude of the distinct structures: the amplitudes of the various patterns increase as the amount of pre-strain increases, while the wavelengths remain constant within our experimental ranges. The experimental results of the wavelengths and amplitudes for the wavy structured patterns of 270-nm-thick a-Si layer are in good agreement with the theoretical solutions of the single crystalline silicon (c-Si) model, which implies that the theoretical modeling of the deformation of c-Si film can be expandable to the case of a-Si film deformations.
Bibliographical noteFunding Information:
This work was partly supported by the IT R&D program of MKE/KEIT [ 10030517-2009-03 , Advanced CMOS image sensor using 3D integration] and by Priority Research Centers Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology [ 2009-0093823 ].
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry