Plasmonic Hot-Electron Effect Enhanced WSe₂ Based Transistor Based on Asymmetric Schottky Contacts for Self-Powered Photodetection and Visual Synapse

Schottky interfaces in metal-semiconductor contacts are crucial in optoelectronics, with a focus on enhancing the detection performance. The plasmonic hot-electron effect offers efficient photon-to-electricity conversion, boosting the sensitivity in self-powered photodetectors as well as expanding detection wavelength ranges and improving the functionality of metal-semiconductor-metal (M₁-S-M₂) structured photodetectors. Utilizing two-dimensional WSe₂ nanoflakes, we fabricate a transistor with a M₁-S-M₂ structure featuring Au and Ag electrodes. Under 405 nm light, we achieve a maximum specific detectivity (<i>D</i>*) of 9.23 × 10¹¹ Jones with a photocurrent density of 4.6 mA cm^-2 and a peak on/off ratio of 6.88 × 10⁵. Compared with the Au/WSe₂/Au transistor also on the poly(ethylene terephthalate) (PET) substrate, the maximum current density measured for the Au/WSe₂/Ag transistor under the light of 405 nm is 1.3 times that of the former, and the <i>D*</i> measured under the light of 1064 nm increases to 20 times the original value; it is now capable of detecting the 1550 nm light, which was undetectable previously. These data clearly demonstrate that the transistor exhibits excellent photodetection performance in the visible and near-infrared spectra. In addition, under biased voltage conditions, the transistor can effectively simulate the visual synaptic behavior under the stimulation of visible light and near-infrared light. Due to its simple structure, wide detection range, excellent light detection performance, and remarkable synaptic plasticity characteristics, this transistor has great potential in various applications of light detection technology and artificial vision systems.