Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 71: Quantum Dots: Optical Properties

HL 71.4: Talk

Thursday, March 17, 2011, 11:00–11:15, POT 251

GaInN quantum dots as optochemical transducers — •Jörg Teubert¹, Sebastian Koslowski¹, Aparna Das², Eva Monroy², Philomela Komninou³, and Martin Eickhoff¹ — ¹I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Germany — ²CEA-CNRS, INAC/SP2M/NPSC, CEA-Grenoble, France — ³Department of Physics, Aristotle University of Thessaloniki, Greece

We report on the sensitivity of photoluminescence (PL) properties of polar InGaN/GaN quantum dot (QD) super-lattices to changes in the chemical environment. III-N QD structures arouse increasing interest e.g. as light emitters in optoelectronics and telecommunication. Here we address the potential of these nanostructures in the field of chemical sensing. We studied the PL response of III-N QDs upon pH-variations in liquid environment. The experimental results demonstrate that InGaN-quantum dot super-lattices (QDSL) are well suited for the fabrication of novel opto-chemical transducers. InGaN/GaN QDSLs were grown by plasma assisted molecular beam epitaxy on AlN-on-sapphire templates. Measurements in liquid environment were performed using a standard three electrode setup and PBS-buffer with HCl admixture as electrolyte. In order to obtain a deeper understanding of the underlying mechanisms, external electric fields were applied in liquid environment along the QDSL. They reveal a superlinear increase of the PL intensity by more than one order of magnitude when changing the bias voltage by only 600 mV. The underlying mechanism will be discussed in terms of an enhanced carrier confinement under applied bias using numerical simulations of the quantum confinement.