Covalent attachment of a peptide to the surface of gallium nitride

The properties of GaN have made it not only an ideal material for high power and high frequency electronic devices, but also a semiconductor suitable for application in biosensing devices. The utilization of GaN in electronic biosensors has increased the importance of characterizing robust and easily implemented organic functionalization methods for GaN surfaces. This work demonstrates and characterizes a route to functionalize the GaN (0001) surface with two organic molecules, hexylamine and a peptide, through olefin cross-metathesis with Grubbs first generation catalyst. The GaN (0001) surface was chlorinated, functionalized with a terminal alkene group using a Grignard reaction, and then terminated with a carboxyl group using an olefin cross-metathesis reaction. With a condensation reaction, the final step in the reaction scheme bound hexylamine or a peptide to the carboxyl terminated GaN surface. Qualitative and quantitative X-ray photoelectron spectroscopy (XPS) data verified the success of each step in the reaction scheme. Surface element composition, adlayer coverages, and adlayer thicknesses were calculated based on the XPS data. At least a monolayer of surface molecules covered the GaN surface.