KEYWORDS: Near field optics, Gold, Plasmonics, Gallium arsenide, Electrodes, Photodetectors, Optimization (mathematics), Nanostructures, Metals, Lab on a chip
This theoretical work explores how various geometries of Au plasmonic nanoslit array structures improve the total optical enhancement in GaAs photodetectors. Computational models studied these characteristics. Varying the electrode spacing, width, and thickness drastically affected the enhancement in the GaAs. Peaks in enhancement decayed as Au widths and thicknesses increased. These peaks are resonant with the incident near-infrared wavelength. The enhancement values were found to increase with decreasing electrode spacing. Additionally, a calculation was conducted for a model containing Ti between the Au and the GaAs to simulate the necessary adhesion layer. It was found that optical enhancement in the GaAs decreases for increasing Ti layer thickness. Optimal dimensions for the Au electrode include a width of 240 nm, thickness of 60 nm, electrode spacing of 5 nm, and a minimum Ti thickness. Optimal design has been shown to improve enhancement to values that are up to 25 times larger than for nonoptimized geometries and up to 300 times over structures with large electrode spacing. It was also found that the width of the metal in the array plays a more significant role in affecting the field enhancement than does the period of the array.
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.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.