and data-center networks 3, 6, 7

Recent progress in artificial intelligence is largely attributed to the rapid development of machine learning, especially in the algorithm and neural network models. However, it is the performance of the hardware, in particular the energy efficiency of a computing system that sets the fundamental limit of the capability of machine learning. Data-centric computing requires a revolution in hardware systems, since traditional digital computers based on transistors and the von Neumann architecture were not purposely designed for neuromorphic computing. A hardware platform based on emerging devices and new architecture is the hope for future computing with dramatically improved throughput and energy efficiency. Building such a system, nevertheless, faces a number of challenges, ranging from materials selection, device optimization, circuit fabrication, and system integration, to name a few. The aim of this Roadmap is to present a snapshot of emerging hardware technologies that are potentially beneficial for machine learning, providing the Nanotechnology readers with a perspective of challenges and opportunities in this burgeoning field.

We report a defect state based guided-wave photoconductive detector at 1360-1630 nm telecommunication wavelength directly in standard microelectronics CMOS processes, with zero in-foundry process modification. The defect states in the polysilicon used to define a transistor gate assists light absorption. The body crystalline silicon helps form an inverse ridge waveguide to confine optical mode. The measured responsivity and dark current at 25 V forward bias are 0.34 A/W and 1.4 μA, respectively. The 3 dB bandwidth of the device is 1 GHz.

Absorption by mid-bandgap states in polysilicon or heavily implanted silicon has been previously utilized to implement guided-wave infrared photodetectors in CMOS compatible photonic platforms. Here, we demonstrate a resonant guided-wave photodetector based on the polysilicon layer that is used for the transistor gate in a microelectronic SOI CMOS process without any change to the foundry process flow (“zero-change” CMOS). Through a combination of doping mask layers, a lateral pn junction diode in the polysilicon is demonstrated with a strong electric field to enable efficient photo-carrier extraction and high-speed operation. This photodetector has a responsivity of more than 0.14 A/W from 1300 to 1600 nm, a 10 GHz bandwidth, and 80 nA dark current at 15 V reverse bias.

No abstract