High-efficiency low-jitter silicon-based single photon avalanche diodes (SPADs)
Abstract/Contents
- Abstract
- Single-photon detectors are known for high sensitivity and picoseconds timing resolution (i.e., low jitter). They have been widely used to push the frontiers in both academic research and industrial products for depth sensing (e.g., LiDAR), quantum key distribution, single-molecule fluorescence, and bio-medical imaging. Among single-photon detectors, Si-based SPADs have gained interest due to their low cost, compact form factor, ease of integration, and compatibility with standard CMOS fabrication techniques. However, in the near-infrared regime of interest (750 nm to 1 μm wavelength), these devices suffer from a clear trade-off between the detection efficiency and jitter due to low optical absorption in silicon. In order to break this trade-off, a Si-SPAD with light trapping effect is demonstrated to significantly improve efficiency at a small jitter. The working principle is to make photons propagate horizontally within the device layer to increase the absorption length. This dissertation mainly focuses on prototyping of light trapping SPADs. After an overview of motivation and physics behind Si-SPADs, we model the SPAD performance in a Monte Carlo simulation to validate and optimize the design. Then, we discuss the fabrication processes starting from material epitaxy. Since nano-structures on SPAD surfaces are a critical component to induce light trapping, we have developed techniques (photoresist reflow and TMAH wet etch) to create nano-structures in a low-cost and CMOS-compatible method. Following fabrication, single photon characterization is performed. We have achieved a 2.5-fold improvement of detection efficiency in the near infrared regime (32% at 850 nm wavelength), while the jitter remains 25 ps. The result proves that we successfully break the current trade-off of Si SPADs. In addition, we have improved efficiency of Si-SPADs in the ultraviolet wavelength regime by creating a gradient doping profile to better collect carriers generated close to surface. The doping profile is achieved by boron vapor phase doping in our epitaxy chamber. After this, an imaging application for Si SPADs is demonstrated, where we record the transient images of light propagating within objects on a 300 ps time scale.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2017 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Zang, Kai |
|---|---|
| Associated with | Stanford University, Department of Electrical Engineering. |
| Primary advisor | Harris, J. S. (James Stewart), 1942- |
| Thesis advisor | Harris, J. S. (James Stewart), 1942- |
| Thesis advisor | Kamins, Theodore I |
| Thesis advisor | Miller, D. A. B |
| Advisor | Kamins, Theodore I |
| Advisor | Miller, D. A. B |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Kai Zang. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2017. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2017 by Kai Zang
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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