Carbon Nanotube Intramolecular Junction Photodetector Via Strain Engineering

In modern photonics, a semiconductor homojunction or heterojunction is the core of optoelectronic devices and photonic integrated circuits. Here, a strategy is demonstrated to create tunable bandgap carbon nanotube intramolecular junctions via uniaxial strain modulation. The fabrication of photodetectors based on this mechanism is controllable, reproducible, and scalable, which is completely superior to other pathways for forming intramolecular junctions. Compared to ordinary detectors without strain, the intramolecular junction photodetector shows an ≈10-fold reduction in dark current and a more than 4 times enhancement in responsivity under zero bias. Furthermore, it is shown that the active area of this short-wave infrared photodetector can be scaled down to 0.5 µm², while maintaining high performance. Significantly, with its tunable spectral response, this work provides a promising and effective approach to engineering various nanotube intramolecular junctions through strain modulation, addressing a critical technological challenge and meeting the demands of optoelectronic applications.