- The paper introduces an on-chip integrated Si-graphene plasmonic Schottky photodetector that leverages plasmonic confinement to boost responsivity and internal quantum efficiency.
- It achieves 85mA/W responsivity at 1.55 µm and a 7% internal quantum efficiency, outperforming traditional metal-silicon photodetectors.
- Avalanche photogain under a 3V reverse bias demonstrates its potential for scalable, CMOS-compatible photonic applications in NIR optical communications.
Overview of On-chip Integrated Silicon-Graphene Plasmonic Schottky Photodetector
The paper presents the development of an on-chip integrated metal-graphene-silicon (M-SLG-Si) plasmonic Schottky photodetector, emphasizing its enhanced responsivity for near-infrared (NIR) applications, particularly at telecom wavelengths around 1.55 µm. This device demonstrates significant improvements in responsivity and internal quantum efficiency (IQE), showcasing the potential integration of graphene with silicon photonics, which represents a promising advancement in the domain of integrated photonic devices.
Technical Details
The reported photodetector achieves an 85mA/W responsivity at 1.55 µm and an internal quantum efficiency of 7%, which is an order of magnitude higher than that of conventional metal-silicon Schottky photodetectors. Under a 3V reverse bias condition, the device exhibits avalanche multiplication characterized by a responsivity of 0.37A/W and an avalanche photogain of approximately 2. The enhanced performance of the photodetector arises from integrating graphene at the Schottky interface, which facilitates plasmonic confinement and improved carrier dynamics.
The architecture of the device involves a compact design with a 5µm-length Si-waveguide integrated with a Schottky diode formed by a graphene/Au contact. This configuration supports surface plasmon polariton (SPP) guiding, which provides optical confinement and enhanced interaction at the interface, thereby boosting light absorption and photogenerated carrier injection into silicon.
Numerical Results
The empirical results presented reveal a marked improvement over traditional designs. Notably, in comparison to reference metal-Si photodetectors, which show responsivity around 9mA/W, the M-SLG-Si photodetector achieves substantially increased responsivity. Under a 3V reverse bias, the introduction of avalanche effects further enhances responsivity to levels comparable with state-of-the-art SiGe photodetectors. These enhancements in responsivity and IQE signify the effectiveness of plasmonic and graphene enhancements in facilitating efficient photodetection at NIR wavelengths.
Implications and Future Developments
The proposed photodetector demonstrates a viable path for integrating graphene with silicon photonics, paving the way for advancing compact, highly responsive optoelectronic devices in the telecom spectral range. The integration approach provides a scalable, CMOS-compatible method that is potentially less complex than current SiGe or III-V semiconductor integrations. Moreover, it opens avenues for practical applications in on-chip optical communications and offers a potential solution to overcome the limitations of Si photodetectors regarding bandwidth and responsivity.
Future developments could involve optimizing the material interface characteristics to further elevate performance metrics such as responsivity and noise tolerance. Additionally, exploring other 2D materials alongside graphene could provide further enhancements and broaden the operational wavelengths of such integrated photodetectors.
Conclusion
The research introduces a sophisticated design for a silicon-graphene photodetector with remarkable performance attributes that could substantially impact the field of integrated optics and photonics. By leveraging the unique properties of graphene at the Schottky interface, this work paves the way for more efficient and compact solutions in silicon photonics, with implications extending into high-speed communication technologies.