Structural Characteristics of Au-GaAs Nanostructures for Increased Plasmonic Optical Enhancement

This research has been performed to improve upon optical qualities exhibited by metallic-semiconductor nanostructures in terms of their ability to excite electrons and generate current through the fabricated device. Plasmonic interactions become very influential at this scale, and can play an important role in the generation of photocurrent throughout the semiconductor. When the device is fabricated to promote the coupling of these radiated electromagnetic fields, a very substantial optical enhancement becomes evident. A GaAs substrate with an array of Au nanowires attached to the surface is studied to determine structural qualities that promote this enhancement. Using computational electromagnetic modeling and analysis, the effect of the Ti adhesion layer and various structural qualities are analyzed to promote photocurrent generation. Emphasis is placed on the amount of enhancement occurring in the semiconductor layer of the model. The photocurrent is then calculated mathematically and generalized for optimization of the device.