Ultra-scaled Phototransistors based on Monolayer MoS2

Abstract For decades, the fundamental diffraction limit of light has stymied the dimension scaling for optoelectronic devices, which remain largely stuck at the micrometer scale or larger. However, recent studies have shown that nanoantennas and plasmonic devices capable of capturing/directing electromagnetic waves are one avenue of artificially focusing incident light into sub-wavelength active areas, thus enabling applications such as photodetection and communication in defiance of the diffraction limit. Despite these advancements, the ultimate scaling limits of photodetector active areas have remained largely untested. In this work, we present a two-dimensional (2D) monolayer molybdenum disulfide (MoS2) photodetector that is able to reach responsivities and detectivities in excess of 108 A/W and 1012 Jones, respectively, and display a high dynamic range while possessing an active area of only 0.0065 μm2. Together, the nano-scale active area and ultra-thin-body nature of the sensing material correspond to an active volume of ~4.23 × 10-6 μm3, approximately 3× smaller than the current smallest photodetector reported in the literature. These results indicate that continued scaling of photodetectors beyond the diffraction limit has enormous potential so long as methods of focusing incident light continued to be developed concurrently.