GaN-based hetero structures for optical sensing

Actually, we investigate, whether GaN-based semiconductor hetero structures can be used as optically driven chemical sensors. As they do not require electrical contacts, but can be read out remotely by light, they are very useful for harsh environment. For the specific detection of bio molecules etc., we intend to functionalize the surface by adequate bio molecules. As sensor signal, the photoluminescence of a near-surface GaInN quantum well is taken, which changes its spectral properties by the band bending influenced by material adsorbed on the semiconductor surface. Besides planar structures, differently structured surfaces will be tested. The sensor material will be fabricated in our GaN group (Prof. Scholz). These studies will be done in close cooperation with Prof. T. Weil (Organic Chemistry, functionalisation of the surface with bio molecules) and Apl. Prof. K. Thonke (Physics/Quantum Matter, optical spectroscopy).

 

Sensor Prinziple: The near-surface band bending of the semiconductor hetero structure and hence the GaInN quantum well luminescence is changed by chemicals adsorbed on the surface (right). This effect is observed for coaxial nano structures (left) as well as for planar quantum wells (center).
Change of photoluminescence intensity of a near-surface GaInN quantum well when in contact with nitrogen or oxygen.