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Toward the Super Temporal Resolution Image Sensor with a Germanium Photodiode for Visible Light
Nguyen Hoai Ngo1, Anh Quang Nguyen2, Fabian M Bufler3
1School of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga 525-8577, Japan.
Sensors (Basel, Switzerland)
|December 5, 2020
Summary
Germanium photodiodes (Ge PDs) offer super temporal resolution, surpassing silicon
Area of Science:
- Optoelectronics
- Semiconductor Physics
- Materials Science
Background:
- Silicon photodiodes (Si PDs) have a theoretical temporal resolution limit of 11.1 ps.
- Achieving 'super temporal resolution' requires exceeding this limit.
Purpose of the Study:
- To investigate Germanium photodiodes (Ge PDs) as a material for achieving super temporal resolution.
- To analyze the theoretical and practical temporal resolution limits of Ge PDs.
Main Methods:
- Utilized Monte Carlo simulations to analyze Ge PD temporal resolution.
- Compared absorption coefficients, saturation drift velocities, and diffusion coefficients of Ge and Si.
Main Results:
- The theoretical temporal resolution limit for Ge PDs was estimated at 0.26 ps, with a practical limit of 1.41 ps.
- Ge PDs offer significantly higher absorption coefficients than Si PDs, enabling thinner devices.
Conclusions:
- Ge PDs demonstrate potential for super temporal resolution, significantly exceeding Si PD limits.
- Developing ultra-high-speed image sensors requires driver circuits operating at ≥100 GHz.
- A phased approach is proposed, starting with SWIR sensors and progressing to smaller Ge PDs.
