Ultrafast, highly-sensitive infrared photodetectors based on two-dimensional oxyselenide crystals

Abstract: Infrared detection and sensing is deeply embedded in modern technology and human society and its development has always been benefitting from the discovery of new photoelectric response materials. The rise of two-dimensional (2D) materials, thanks to their distinct electronic structure, extreme dimensional confinement and strong light-matter interactions, provides new material platform for next-generation infrared photodetection. Ideal infrared detectors should have fast respond, high sensitivity and air-stability, which is rare to meet at the same time for all existing 2D materials, either graphene, transition metal dichalcogenide or black phosphorous. Herein we demonstrate a new infrared photodetector based on 2D Bi2O2Se crystals, whose main characteristics are superb in the whole 2D family: high sensitivity of ~65 A/W at 1200 nm and ultrafast intrinsic photoresponse of ~1 ps at room temperature. Such great performance is attributed to the suitable electronic bandgap and high carrier mobility of 2D oxyselenide. With additional merits of mass production, excellent stability and flexibility, 2D oxyselenide detectors should open new avenues in highly-sensitive, high-speed, low-cost, flexible infrared photodetection and imaging.

• The paper demonstrates that 2D Bi2O2Se photodetectors achieve ~65 A/W sensitivity at 1200 nm and a ~1 ps photoresponse.
• The researchers use chemical vapor deposition to fabricate stable, ultrafast, and flexible detectors compatible with silicon-based circuits.
• The study highlights the material’s high carrier mobility and robustness, promising transformative advances in IR sensing and imaging applications.

Ultrafast, Highly-Sensitive Infrared Photodetectors Based on Two-Dimensional Oxyselenide Crystals

The development and advancement of infrared (IR) photodetectors are essential for a wide array of applications ranging from telecommunications to medical diagnostics. Recent research by Yin et al. has unveiled a promising new entrant in the field: an IR photodetector fabricated using two-dimensional (2D) oxyselenide crystals, specifically 2D Bi2O2Se. This paper posits that these photodetectors demonstrate superior sensitivity and ultrafast photoresponse when compared to existing 2D materials, and they operate with remarkable stability and efficiency at room temperature.

The inherent characteristics of 2D Bi2O2Se crystals, such as their suitable electronic bandgap and high carrier mobility, make them noteworthy candidates for next-generation photodetective applications. The sensitivity of this 2D oxyselenide photodetector reaches approximately 65 A/W at 1200 nm, a significant improvement over other 2D materials which struggle in the infrared spectral range. This level of sensitivity ensures the detector's capability to perceive even weak infrared signals, which is pivotal for various practical applications.

Further, the photoresponse speed of these photodetectors is ultra-fast, with intrinsic response times reaching as low as ~1 ps, thus allowing them to handle frequencies up to ~1 THz. This performance is analogous to that of 2D Dirac materials such as graphene, while also offering an appreciable bandgap, suggesting high efficiency in free carrier generation with minimal energy loss. These attributes point to the potential of 2D Bi2O2Se in fulfilling the high-speed and high-sensitivity demands of modern infrared photodetection and imaging.

Beyond their performance metrics, the structural and chemical properties of 2D Bi2O2Se material offer additional advantages. The oxyselenide structures exhibit excellent stability in exposed air conditions over extended durations (months), and they maintain operational flexibility under strain (up to ~1%). This robustness and flexibility hint at a promising future for integration into flexible biosensors and other advanced technological applications.

The fabrication of these photodetectors is achieved using chemical vapor deposition, allowing for ease of integration with existing semiconductor technologies and potential mass production. The layered nature of Bi2O2Se, with alternately stacked Bi-O and Se layers, facilitates the creation of devices down to few atomic layers, fostering the high mobility necessary for effective photocarrier extraction.

The implications of this research extend towards transformative changes in IR sensing technologies. Aligning with current trends, the compatibility of these detectors with silicon-based readout circuits positions them optimally for cutting-edge hybrid systems, potentially enhancing pixel density and processing capabilities of IR imaging devices. Such integration could lead to more complex on-chip processing and bolster applications spanning from night vision technologies to enhanced environmental sensing.

In summary, the paper by Yin et al. significantly advances our understanding and capabilities in the field of infrared photodetection using novel 2D oxyselenide materials. The combined attributes of high sensitivity, rapid response time, environmental stability, flexibility, and ease of fabrication articulate a compelling case for 2D Bi2O2Se as a material of choice for future IR sensing technologies. Further research and development could see these materials revolutionizing various sectors reliant on IR photodetection and imaging, pointing towards both immediate applications in technology and broader implications for the theoretical understanding of 2D materials in photonics.