Broadband, high responsivity, fast graphene-quantum dot photodetectors with wafer-scale processing
New research shows hybrid graphene field-effect transistor quantum dot (GFET-QD) photodetectors fabricated on a 200-mm wafer platform. These devices have high yield (96%) and low variability as well as impressive sensitivity (10^5 to 10^6 V/W) over a wide wavelength range (400 to 1800 nm). The GFET QD architecture enables photovoltage adjustment through the gate, making them suitable for electrical shutter operation. Highlights of the research, which was recently published in Scientific Reports, include successful integration with complementary metal-oxide-semiconductor (CMOS) technology and stability under operating conditions. The research highlights the scalability and reproducibility of production necessary for commercialization and describes the innovative processes used to produce high-quality graphene and quantum dots. Overall, the results represent a significant step towards practical applications of graphene-based photodetectors in imaging systems.
GFET-QD hybrid photodetectors can be used in various applications of imaging systems, ranging from surveillance, search and rescue, and vehicle safety, to improved sorting of food and food packaging to reduce their environmental impact. The pivotal advantage of GFET-QD photodetectors is in their high sensitivity and fast response time. The manufacturing process incorporates advanced techniques such as chemical vapor deposition for high quality graphene and meticulous layer transfer methods that contribute to low defect concentration and high areal uniformity, resulting in impressive yield rates.
Figure: Device architecture, operational principle, and optical microscope image. From Li et al, DOI: 10.1038/s41598-025-96207-z, under CC BY 4.0 license.
Key challenges overcome during the research include ensuring scalable production processes, reproducibility and integration with existing silicon technologies to meet commercial manufacturing requirements. This was made possible by solving several problems in the integration of graphene at wafer scale, such as chemical vapor deposition (CVD), transfer and patterning of single-layer graphene. These processes ensure compatibility with imaging functionalization and enable large area deposition of the multilayer quantum dot (QD) absorber material under an inert atmosphere. Encapsulation techniques such as thin film alumina (Al₂O₃) coatings and hermetically sealed semiconductor packages were also used. This demonstration takes the original concept to a higher technological level in several dimensions, including the statistics of wafer-scale graphene devices, the development of customized CMOS circuits and the implementation of production-ready packaging solutions.
The integration with CMOS technology enables the development of more compact and efficient imaging sensor arrays, which can lead to lower production costs and improved device functionality, taking graphene photodetectors to a higher technology readiness level (TLR).
