Design, simulation, and fabrication of nanostructures for optoelectronic applications
Abstract/Contents
- Abstract
- Improving the efficiency of semiconductor optoelectronic devices is a central pursuit on the path to affordable, universal access to solar power, energy-efficient lighting, sensitive photodetectors, and vibrant display technologies. In all of these applications, light must pass through an interface between the device and the outside world. Nanostructures on the scale of the wavelength of light offer a powerful way to control the flow of light through this interface, which could enable devices with new functionality and dramatically improved optical efficiency. However, nanostructured surfaces also present some interesting design challenges. Here, I will present three case studies illustrating the promise and challenges of nanostructured interfaces in optoelectronic applications. First, I will present a camera sensor architecture that is able to capture the full light field from a scene, enabling 3D image reconstruction and focusing after the photo is taken. By stacking polymer microspheres on silicon nanoshells, we can focus and confine light in a very small volume. Using this coupled system, we are able to resolve the angle of light incident at up to 40 degrees away from the normal. By contrast, microlenses on a planar substrate can only resolve angles up to 10 degrees away from the normal. Second, I will discuss vacuum photocathodes, which are currently used in low-light detectors and electron sources and have the potential to be used in solar energy generation systems. I will present a simulation suite that models the optical and electronic behavior of photocathodes, offering new insight into nanostructured architectures that should maximize electron yield. In particular, the anti-reflection properties of the surface must be carefully balanced against nanostructured profiles that block electron emission. I will also present measurements we made of photoemission from nanostructured photocathodes to highlight the importance of developing interfaces with low surface recombination and to motivate a study on the passivation of gallium arsenide using gallium nitride. Third, I will describe a new hybrid optoelectronic interface that offers both high light transmission and high electrical conductivity. We use metal-assisted chemical etching (MACE) to create a silicon substrate that is covered by a gold film with protruding silicon nanopillars. When coated with a silicon nitride anti-reflection layer, we observe up to 97% absorption in this structure, which is remarkable considering that metal covers 60% of the top surface. We use optical simulations to show that Mie-like resonances in the nanopillars funnel light around the metal layer and into the substrate, offering a general paradigm for creating ultra-transparent metal contacts for solar cells, displays, and more.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Narasimhan, Vijay Kris |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering. |
| Primary advisor | Cui, Yi, 1976- |
| Primary advisor | Melosh, Nicholas A |
| Thesis advisor | Cui, Yi, 1976- |
| Thesis advisor | Melosh, Nicholas A |
| Thesis advisor | Brongersma, Mark L |
| Advisor | Brongersma, Mark L |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Vijay Kris Narasimhan. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Vijay Kris Narasimhan
- License
- This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).
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