High-performance single SiC nanocable-based plasmonic photodetectors for ultraviolet communication systems

Abstract

Silicon carbide (SiC) nanowires are the most promising candidate for developing high-performance single-nanowire-based UV photodetector (PD) with outstanding photoelectronic properties and low power consumption. However, SiC single-nanowire-based UV PDs commonly suffer from very low light current on the order of pA or nA, requiring precision equipment or an extra current amplification circuit, which greatly limit their practical application. To overcome this bottleneck, novel SiC single nanocable-based plasmonic PDs with the light current on the order of mA were successfully developed with the features of improving light absorption and reducing the dark current. The SiC/SiO₂@Ag nanocables consisting of SiC nanowire core and uniform SiO₂ shell encrusted with scattered and isolated Ag nanoparticles (NPs) were fabricated by a simple, low-cost, and space-confined vacuum-heating strategy using ultralong SiC nanowires and silver nitrate precursor followed by the annealing process. In such architecture, the in situ resulting SiO₂ shell can effectively passivate the surface defects of the SiC nanowire core, restrain the photo-excited carrier's losses, and effectively block the hot electron injection, leading to a great reduction in the dark current and enhancement in the light current. The encrusted Ag NPs on the nanocable surface exhibited a strong LSPR effect with significantly increased optical absorption. Benefiting from the synergistic effect of SiO₂ passivation and Ag nanoparticle LSPR effect, the device current increased dramatically by several orders of magnitude to reach 0.37 mA at a bias voltage of 3 V. Moreover, the developed SiC/SiO₂@Ag PDs had faster response speed (0.27 s), lower dark current at the nA level, and high stability, which can be competent for the development of real-time, accurate, and cost-effective communication systems and flame detection with impressive switching ratio as high as 66012.