Theoretical studies of rolled-up and wrinkled nanomembranes
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Abstract
The thesis is devoted to three similar topics from the field of rolled-up and wrinkled nanomembranes. We start by recalling classical theory of thin plates, which will be used to describe deformation of nanomembranes. In the first topic, relaxation of internal strain is studied when a flat film is partially released from the substrate by etching the sacrificial layer underneath. Energetic competition of the tube and wrinkle shape is quantitatively investigated. Similar model is used to investigate the limiting maximum value of tube rotations. In the second topic, roll-up of initially wrinkled film is shown to favor tubes forming on the flat edge of rectangular wrinkled pattern, enabling precise control of tube position. Experiment is provided to justify our theoretical predictions. In the third topic, quantum well is assumed inside a wrinkled nanomembrane. Shift of transition energy induced by lateral modulation due to bending strain is quantified, being of interest for strain-sensitive optical detectors and emitters. In addition, lateral localization of electron and hole due to strain is also studied.
Additional movie files:
NMP1_5x_flat - Rolling of flat film, Fig. 3.16, left column
NMP1_5x - Rolling of wrinkled 'step' film, Fig. 3.16, right column
Credits
Charles University, Prague, Czech Republic
Publications
1. Cendula, P., S. Kiravittaya, Y. F. Mei, Ch. Deneke, and O. G. Schmidt. "Bending and Wrinkling as Competing Relaxation Pathways for Strained Free-hanging Films." Physical Review B 79, 085429 (2009).
2. Cendula P., Kiravittaya S., Monch I., Schumann J., and Schmidt O. G., "Directional Roll-up of Nanomembranes Mediated by Wrinkling", Nano Lett. 11, 236 (2011).
3. Cendula P., Kiravittaya S. and Schmidt O. G., to appear in Journal of Applied Physics (2012), http://arxiv.org/abs/1107.1043.
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