Graphene Quantum Dots Promoted the Synthesis of Heavily n-Type Graphene for Near-Infrared Photodetectors

The application of graphene in the field of microelectronics is becoming more and more urgent with the emergence of bottlenecks in semitechnical development, in which controllable graphene doping technology, therefore, strongly demanded to tune the electronic or optoelectronic properties for the fabrication of high-performance devices. We herein report a simple and convenient approach to synthesize heavily nitrogen (N) and phosphorus (P) codoped graphene (n-type graphene) by chemical vapor deposition (CVD), which is realized by utilizing N and P codoped graphene quantum dots (n-type GQDs) as nucleation centers, methane (CH₄) as the gaseous carbon reservoir, and copper (Cu) foils as the catalyst substrate. By the monitoring of the growth mechanism of the graphene, and an investigation revealed that codoped GQDs could serve as the nucleation sites for producing doped-graphene films through two-dimensional epitaxial growth. Finally, the photodetector built on the heavily n-type graphene film is confirmed to perform satisfactorily, accompanying high detectivity (∼1.3 × 10¹⁰ cm Hz^1/2 W^-1) and responsivity (58 mAW^-1), at a wavelength of 1550 nm. A simple and environmentally friendly graphene doping technology has been developed, which promotes the application of doped graphene in the field of microelectronics.