A gallium nitride-based nitric oxide sensor

Because of its importance in biological, environmental, and defense applications, it is desirable to selectively and sensitively detect Nitric Oxide (NO) with a device that will monitor its concentration continuously.; GaN-based HFET structures, which are highly sensitive to surface charge states due to the nature of the formation of their two-dimensional electron gas (2DEG), were grown and investigated in this study to detect NO gas. Furthermore, in this thesis the author devised a novel approach for obtaining electrical data for NO gas detection using the established van der Pauw (VDP) method. Additionally, this research explored the functionalization of the GaN surface with hemin porphyrins to enhance selectivity and sensitivity. The relevance of hemin with NO physiology is well established and was the impetus for exploring the porphyrins with this work. XPS analysis indicates that we successfully functionalized GaN templates and GaN HFET structures with the hemin-Cl porphyrin group. Although this functionalization method is similar to previous work, the application of this process to a GaN materials system is new. Our results from this VDP experiment show that both the functionalized and non-functionalized GaN HFET samples demonstrated significant changes in sheet resistivity, that follow time-dependent Langmuir adsorption kinetic behavior, due to increased concentrations of NO in a controlled gaseous environment. This method appears promising for providing an initial proof of concept for NO sensors on a GaN platform.