GaN Quantum Dots as Optical Transducers in Field Effect Chemical Sensors

Quantum dots (QDs) are of special interest for both fundamental physics and optoelectronic applications. Controlled growth of ensembles of self assembled GaN/AlN QDs showing efficient room-temperature luminescence has been demonstrated recently. On the other hand, GaN-based devices have been shown useful to detect chemically induced changes of the surface potential, thereby acting as chemical sensors in liquid or gaseous environments. We demonstrate the applicability of GaN QDs embedded in an AlN matrix and covered with a catalytic Pt layer as chemical sensors with contactless optical readout, benefiting from the optical transparency of both the sapphire substrate and the AlN matrix. The optical response of such a system in terms of a change in luminescence characteristics upon exposure to hydrogen is discussed.