A novel bio-functionalization of AlGaN/GaN-ISFETs for DNA-sensors

AlGaN/GaN pH sensitive devices were functionalized and passivated for the use as selective biosensors. For the passivation, a multilayer of SiO2 and SiNx is proposed, which stabilizes the pH-sensor, is biocompatible and has no negative impact on the following bio-functionalization. The functionalization of the GaN-surface was achieved by covalent bonding of 10-amino-dec-1-ene molecules by a photochemical process. After exposure to ultraviolet light, islands of TFAAD are growing on the sensor surface. After 3 h exposure one monolayer is completed. Further exposure results in thicker films as a consequence of polymerization. The bonding to the sensor surface was analyzed by x-ray photo electron spectroscopy, while the thickness of the functionalization was determined by atomic force microscopy scratching experiments. These functionalized devices based on the pH-sensitive AlGaN/GaN ISFET will establish a new family of adaptive, selective biomolecular sensors such as selective, reusable DNA sensors.