arXiv subjects

Suwit Kiravittaya

Publications and source records attributed to Suwit Kiravittaya.

5 recordsLinked to original sources

arXiv2014

Experimental realization of coexisting states of rolled-up and wrinkled nanomembranes by strain and etching control

Self-positioned nanomembranes such as rolled-up tubes and wrinkled thin films have been potential systems for a variety of applications and basic studies on elastic properties of nanometer-thick systems. Although there is a clear driving force towards elastic energy 1 minimization in each system, the exploration of intermediate states where specific characteristics could be chosen by a slight modification of a processing parameter had not been experimentally realized. In this work, arrays of freestanding III-V nanomembranes (NM) supported on one edge and presenting a coexistence of these two main behaviors were obtained by design of strain conditions in the NMs and controlled selective etching of patterned substrates. As the etching process continues a mixture of wrinkled and rolled-up states is achieved. For very long etching times an onset of plastic cracks was observed in the points with localized stress. The well- defined morphological periodicity of the relaxed NMs was compared with finite element simulations of their elastic relaxation. The evolution of strain in the NMs with etching time was directly evaluated by X-ray diffraction, providing a comprehensive scenario of transitions among competing and coexisting strain states.

cond-mat.mes-hall↗

arXiv2010

Absence of anomalous interactions in the quantum theory of constrained charged particles in presence of electrical currents

The experimental progress in synthesizing low-dimensional nanostructures where carriers are confined to bent surfaces has boosted the interest in the theory of quantum mechanics on curved two-dimensional manifolds. It was recently asserted that constrained electrically charged particles couple to a term linear in A_3 M, where A_3 is the transversal component of the electromagnetic vector potential and M the surface mean curvature, thereby making a dimensional reduction procedure impracticable in the presence of fields. Here we resolve this apparent paradox by providing a consistent general framework of the thin-wall quantization procedure. We also show that the separability of the equation of motions is not endangered by the particular choice of the constraint imposed on the transversal fluctuations of the wavefunction, which renders the thin-wall quantization procedure well-founded. It can be applied without restrictions.

cond-mat.mes-hall↗

arXiv2010

Heterogeneous confinement in laterally coupled InGaAs/GaAs quantum dot molecules under lateral electric fields

We study the electronic and optical properties of laterally coupled InGaAs/GaAs quantum dot molecules under lateral electric field. We find that electrons perceive the double-dot structure as a compound single object, while the holes discern two well separated dots. Through a combination of predictive atomistic modeling, detailed morphology studies, and single object micro-photoluminescence measurements, we show that this peculiar confinement results in an unusual heterogeneous behavior of electrons and holes with profound consequences on optical properties.

cond-mat.mes-hall↗

arXiv2006

Semiconductor sub-micro-/nanochannel networks by deterministic layer wrinkling

we demonstrate a technology "Release and bond-back of layers (REBOLA)" that exploits the deterministic wrinkling of a semiconductor layer to create well-defined and versatile nanochannel networks. In linear networks, the periodicity of branch channels as a function of etch-width was analyzed and compared with theoretical calculations. A self-similar folding phenomenon of wrinkles near a fixed boundary was revealed by autocorrelation analysis. The formation of branch channels within circular networks was studied on different length scales and was controlled by the size of the etched circular network and the shape of the initial pattern. To elucidate the usefulness of REBOLA, we exemplified nanofluidic transport as well as femto-litre filling and emptying of individual wrinkles on a standard semiconductor substrate, in which corner flow played an important role.

cond-mat.mtrl-sci↗

arXiv2006

{\it In-situ} Laser Microprocessing at the Quantum Level

One of the biggest challenges of nanotechnology is the fabrication of nano-objects with perfectly controlled properties. Here we employ a focused laser beam both to characterize and to {\it in-situ} modify single semiconductor structures by heating them from cryogenic to high temperatures. The heat treatment allows us to blue-shift, in a broad range and with resolution-limited accuracy, the quantized energy levels of light and charge carriers confined in optical microcavities and self-assembled quantum dots (QDs). We demonstrate the approach by tuning an optical mode into resonance with the emission of a single QD and by bringing different QDs in mutual resonance. This processing method may open the way to a full control of nanostructures at the quantum level.

cond-mat.mtrl-sci↗