arXiv subjects

S. Kiravittaya

Publications and source records attributed to S. Kiravittaya.

5 recordsLinked to original sources

arXiv2012

Bending and wrinkling as competing relaxation pathways for strained free-hanging films

An equilibrium phase diagram for the shape of compressively strained free-hanging films is developed by total strain energy minimization. For small strain gradients Δε, the film wrinkles, while for sufficiently large Δε, a phase transition from wrinkling to bending occurs. We consider competing relaxation mechanisms for free-hanging films, which have rolled up into tube structures, and we provide an upper limit for the maximum achievable number of tube rotations.

cond-mat.mes-hall↗

arXiv2011

Electronic and optical properties of quantum wells embedded in wrinkled nanomembranes

The authors theoretically investigate quantum confinement and transition energies in quantum wells (QWs) asymmetrically positioned in wrinkled nanomembranes. Calculations reveal that the wrinkle profile induces both blue- and redshifts depending on the lateral position of the QW probed. Relevant radiative transistions include the ground state of the electron (hole) and excited states of the hole (electron). Energy shifts as well as stretchability of the structure are studied as a function of wrinkle amplitude and period. Large tunable bandwidths of up to 70 nm are predicted for highly asymmetric wrinkled QWs.

cond-mat.mes-hall↗

arXiv2010

Directional Roll-up of Nanomembranes Mediated by Wrinkling

We investigate the relaxation of rectangular wrinkled thin films intrinsically containing an initial strain gradient. A preferential rolling direction, depending on wrinkle geometry and strain gradient, is theoretically predicted and experimentally verified. In contrast to typical rolled-up nanomembranes, which bend perpendicular to the longer edge of rectangular patterns, we find a regime where rolling parallel to the long edge of the wrinkled film is favorable. A non-uniform radius of the rolled-up film is well reproduced by elasticity theory and simulations of the film relaxation using a finite element method.

cond-mat.mes-hall↗

arXiv2008

Direct strain and elastic energy evaluation in rolled-up semiconductor tubes by x-ray micro-diffraction

We depict the use of x-ray diffraction as a tool to directly probe the strain status in rolled-up semiconductor tubes. By employing continuum elasticity theory and a simple model we are able to simulate quantitatively the strain relaxation in perfect crystalline III-V semiconductor bi- and multilayers as well as in rolled-up layers with dislocations. The reduction in the local elastic energy is evaluated for each case. Limitations of the technique and theoretical model are discussed in detail.

cond-mat.mtrl-sci↗

arXiv2007

Bidirectional wavelength tuning of semiconductor quantum dots as artificial atoms in an optical resonator

We consider a pair of artificial atoms with different ground state energies. By means of finite element calculations we predict that the ground state energies can be tuned into resonance if the artificial atoms are placed into a flexible ring structure, which is elastically deformed by an external force. This concept is experimentally verified by embedding a low density of self-assembled quantum dots into the wall of a rolled up micro tube ring resonator. We demonstrate that quantum dots can elastically be tuned in- and out of resonance with each other or with the ring resonator modes.

cond-mat.other↗