GaInN Quantum Wells as Optochemical Transducers for Chemical Sensors and Biosensors

In this paper, investigations on gallium indium nitride (GaInN) quantum well structures as optochemical transducers in (bio)chemical sensing are presented. In contrast to the conventional electrical read-out of III-nitride-based sensors, a purely optical photoluminescence read-out is performed. A significant spectral shift of the quantum well photoluminescence is observed with varying surface modification. The spectral photoluminescence shift can be attributed to an externally induced quantum confined Stark effect caused by the adsorbed species deposited on the quantum well surface. In order to improve the sensitivity of the transducer elements, different chemical surface treatments are studied. In particular, optical sensing experiments with reducing and oxidizing gases are performed in order to investigate the quantum well photoluminescence response. Additionally, optical investigations of the iron-storage molecule ferritin with varying iron load are presented. The iron load of this molecule is generally considered as a superior biomarker for severe illnesses, such as Alzheimer's disease. In contrast to conventional fluorescent labels, GaInN quantum wells provide a much more stable luminescence signal, and hence, are promising candidates for next generation bioanalytical sensor structures.