Carbon Nanotube-Based Rectenna Architecture for Self-Powered Near-Infrared Selective Photodetection

Self-powered near-infrared (NIR) photodetectors based on silicon are typically broadband and junction-driven, limiting spectral discrimination without external filters. Here, a geometry-selective rectenna platform is demonstrated by integrating carbon nanotubes (CNTs), specifically horizontally aligned multiwalled CNTs (HA-MWCNTs), with a Pt/Al 2 O 3 /Si metal-insulator-semiconductor (MIS) diode. A CNT-free control device and Pt/CNT/Al 2 O 3 /Si devices with defined CNT lengths of 200, 400, 600, and 800 nm are compared under 405, 650, and 980 nm illumination. The control device establishes a silicon-dominated spectral baseline, whereas CNT integration enhances the illuminated response while preserving similar dark rectification. Among the investigated wavelengths, the strongest response was measured for the 200 nm device under 980 nm illumination, reaching approximately 2.3 μA at 1.0 V and 5.4 A W -1 . Stable switching is obtained with rise and fall times of approximately 20 and 29 ms, respectively. At zero external bias, the same device produces a short-circuit current of approximately 0.03 μA and an open-circuit photovoltage magnitude of approximately 94 mV. Electron microscopy, electron energy-loss spectroscopy, and finite-element simulations support a substrate-loaded CNT nanoantenna mechanism, establishing a silicon-compatible route toward compact, self-powered, geometry-tunable NIR photodetectors.