CMOS-compatible neuromorphic devices for neuromorphic perception and computing: a review

Neuromorphic computing is a brain-inspired computing paradigm that aims to construct efficient,low-power,and adaptive computing systems by emulating the information processing mechanisms of biological neural systems.At the core of neuromorphic computing are neuromorphic devices that mimic the functions and dynamics of neurons and synapses,enabling the hardware implementation of artificial neural networks.Various types of neuromorphic devices have been proposed based on different physical mechanisms such as resistive switching devices and electric-double-layer transistors.These devices have demonstrated a range of neuromorphic functions such as multistate storage,spike-timing-dependent plasticity,dynamic filtering,etc.To achieve high performance neuromorphic computing systems,it is essential to fabricate neuromorphic devices compatible with the complementary metal oxide semiconductor(CMOS)manufacturing process.This improves the device’s reliability and stability and is favorable for achieving neuromorphic chips with higher integration density and low power consumption.This review summarizes CMOS-compatible neuromorphic devices and discusses their emulation of synaptic and neuronal functions as well as their applications in neuromorphic perception and computing.We highlight challenges and opportunities for further development of CMOS-compatible neuromorphic devices and systems.

CMOS-compatible all-optical modulator based on the saturable absorption of graphene

Graphene resting on a silicon-on-insulator platform offers great potential for optoelectronic devices.In the paper,we demonstrate all-optical modulation on the graphene-silicon hybrid waveguides(GSHWs)with tens of micrometers in length.Owing to strong interaction between graphene and silicon strip waveguides with compact light confinement,the modulation depth reaches 22.7%with a saturation threshold down to 1.38 pJ per pulse and a 30-μm-long graphene pad.A response time of 1.65 ps is verified by a pump-probe measurement with an energy consumption of 2.1 pJ.The complementary metal-oxide semiconductor compatible GSHWs with the strip configuration exhibit great potential for ultrafast and broadband all-optical modulation,indicating that employing two-dimensional materials has become a complementary technology to promote the silicon photonic platform.

Ag-catalyzed GaSb nanowires for flexible near-infrared photodetectors

High-quality narrow bandgap semiconductors nanowires(NWs)challenge the flexible near-infrared(NIR)photodetectors in next-generation imaging,data communication,environmental monitoring,and bioimaging applications.In this work,complementary metal oxide semiconductor-compatible metal of Ag is deposited on glass as the growth catalyst for the surfactantassisted chemical vapor deposition of GaSb NWs.The uniform morphology,balance stoichiometry,high-quality crystallinity,and phase purity of as-prepared NWs are checked by scanning electron microscopy,energy dispersive X-ray spectroscopy,high-resolution transmission electron microscopy,and X-ray diffraction.The electrical properties of as-prepared NWs are studied by constructing back-gated field-effect-transistors,displaying a high I_(on)/I_(off) ratio of 10^(4) and high peak hole mobility of 400 cm^(2)/(V·s).Benefiting from the excellent electrical and mechanical flexibility properties,the as-fabricated NW flexible NIR photodetector exhibits high sensitivity and excellent photoresponse,with responsivity as high as 618 A/W and detectivity as high as 6.7×10^(10) Jones.Furthermore,there is no obvious decline in NIR photodetection behavior,even after parallel and perpendicular folding with 1200 cycles.

Light spectral filtering based on spatial adiabatic passage

We present the first experimental realization of a light spectral filter based on the spatial adiabatic passage technique.We demonstrate that a fully integrable CMOS-compatible system of three coupled identical total internal reflection silicon oxide waveguides with variable separation along their propagation direction can be used simultaneously as a low-and high-pass spectral filter within the visible range of wavelengths.Light is injected into the right waveguide,and after propagating along the system,long wavelengths are transferred into the left output,whereas short wavelengths propagate to the right and central outputs.The stopband reaches values up to 211 dB for the left output and approximately 220 dB for the right plus central outputs.The passband values are close to 0 dB for both cases.We also demonstrate that the filtering characteristics of the device can be controlled by modifying the parameter values,which define the geometry of the triple-waveguide system.However,the general filtering behavior of the system does not critically depend on technological variations.Thus,the spatial adiabatic passage filtering approach constitutes an alternative to other integrated filtering devices,such as interference or absorbance-based filters.