Ultrafast Carbon Nanotube Photodetectors with Bandwidth over 60 GHz

The future interconnect links in intra- and interchip require a photodetector with high bandwidth, ultrawide waveband, compact footprint, low cost, and compatible integration process with silicon complementary metal–oxide–semiconductor (CMOS) technology. Here, we demonstrate a CMOS-compatible carbon nanotube (CNT) photodetector that exhibits high responsivity, high bandwidth, and broad spectral operation over all optical telecommunication bands based on high-purity CNT arrays asymmetrically contacted by palladium and hafnium electrodes. The ultrafast CNT photodetector demonstrates the 100 Gbit/s Nyquist-shaped on–off keying (OOK) signal transmission, which can address the demand for high-speed optical interconnects in and between data centers. Furthermore, the photodetector exhibits a bandwidth over 60 GHz by scaling down the active area to 20 μm 2 . As the CNT photodetectors are fabricated by a doping-free process, it also provides a cost-effective solution to integrate CNT photonic devices with CNT-based CMOS-integrated circuits. Our work paves a way for future CNT-based high-speed optical interconnects and optoelectronic-integrated circuits (OEICs).