Free-Space Schottky Graphene/Silicon Photodetectors Operating at 2 ?m

This paper presents the design, fabrication, and characterization of Schottky graphene/silicon photodetectors that operate at a wavelength of 2 ?m. These graphene/silicon junctions are carefully characterized using electric and optical measurements over the temperature range from 280-315 K. The photodetectors show external responsivity of 0.16 mA/W at room temperature under zero bias conditions, which is in excellent agreement with the theoretical predictions. In addition, the device performance is discussed in terms of the noise equivalent power and operating bandwidth. To the best of our knowledge, these are the first Si-based photodetectors designed for operation in free space at 2 ?m. The proposed devices will pave the way toward development of hybrid graphene-Si free-space illuminated photodetectors operating at 2 ?m for applications including free-space optical communications, optical coherence tomography and light-based radar systems.