Deposition of the Immobilization Layer 3-Aminopropyltriethoxysilane on Gallium Nitride for Extremophile-Based Biosensors

Biosensors composed of biomolecules and electromechanical components have enabled new sensing modalities for chemical sensing, pathogen detection and disease therapy. Traditional biosensors are silicon-based, but silicon has a known limited radiation lifetime. Gallium nitride (GaN), however, is radiationhard and shows potential for use in biosensors to detect radiation. To support the development of a biosensor based on GaN and the radiation-tolerant extremophile bacteria Deinococcus radiodurans (D. radiodurans), we studied the attachment of an interfacial organosilane immobilization layer to GaN. More specifically, we attached 3-aminopropyltriethoxysilane (APTES) to GaN using molecular layer deposition. We defined the shape of the layer using die-level photolithography and liftoff, and we used goniometry, ellipsometry, and fluorescence microscopy to characterize the attachment properties of this layer. Optimization of this attachment will allow for longlasting radiation detectors for applications such as medical radiation therapy and deep space exploration.