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Group III-nitride quantum dots as optical transducers for chemical sensors
The objective of DOTSENSE is the application of III-nitride (InxGa1-xN) quantum dots (QDs) and nanodisks (NDs) as opto-chemical transducers for the detection of hydrogen, hydrocarbons and the pH-value in gaseous and liquid environments. The characteristics of intense room-temperature luminescence from III-nitride nanostructures can be altered by chemically induced variations of the surface potential. The transparency of the substrate material and the involved buffer layers allow optical excitation and detection of the changes in QD or ND luminescence from the substrate backside. These transducers are hence capable of operating in harsh environments (high pressure, explosive media), as neither electrical feedthroughs nor a deterministic current are necessary for the sensor signal read-out. Furthermore, spatially-resolved detection of variations in the surface potential is possible, since the spatial extension of excited nanostructures is determined by the diameter of the incident light beam.
In the first part of the project, the work is focused on the optimization of the structural properties of QD and ND ensembles (size, alloy composition, number of layers, crystallographic orientation) with the aim of attaining a maximum sensitivity of the emission properties (intensity and energetic distribution) upon variations in the surface potential.
In a second stage, the opto-chemical transducers will be integrated with commercially available light emitters and detectors, to implement different kinds of sensor systems, which demonstrate and exploit the advantages of this innovative transducer concept. These prototypes find application in the field of aeronautics, with a the potential to increase the safety and/or the economy of flying.