Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 94: Quantum wires and nanocrystals: Optical properties
HL 94.1: Talk
Friday, March 15, 2013, 09:30–09:45, H13
GaN nanowires as opto-chemical sensors — •Jens Wallys1, Sara Lippert1, Florian Furtmayr1,2, Sebastian Koslowski1, Jörg Schörmann1, Jörg Teubert1, and Martin Eickhoff1 — 1I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Germany — 2Walter Schotky Institut, Technische Universität München, Germany
GaN nanowires (NWs) grown by plasma-assisted molecular beam epitaxy (PAMBE) feature a low density of structural defects and a high surface to volume ratio. Their electrochemical stability and strong luminescence at room temperature make them promising candidates for opto-chemical sensor applications.
In this contribution we examine Si-, Ge-, and Mg-doped GaN NW ensembles with different doping concentrations in contact with an electrolyte by photoluminescence (PL) spectroscopy and investigate the PL changes related to variations in the chemical environment. With a three electrode setup the potential at the NW electrode can be precisely controlled to optimize the signal response for specific sensing applications e.g. detection of small pH variations caused by biological systems.
The influences of doping with shallow donors (Si or Ge) or acceptors (Mg) on the response characteristics are discussed in terms of achievable sensitivity, detection energy, and measurement stability. The results will be discussed using a qualitative model for the PL response taking non-radiative surface recombination and charge transfer from the NWs to the electrolyte into account.