Atomically Thin Synaptic Devices for Optoelectronic Neuromorphic Vision

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/admt.202201772.

Visible-Active Artificial Synapses Based on Ultrathin Indium Oxide

“…These In 2 O 3 synapses can be used in the future for weight updating in convolutional neural networks, where the devices can be set optically and reset electrically for data recognition purposes. 9,21 ■ CONCLUSIONS Large-area atomically thin In 2 O 3 is used to demonstrate visible light-activated atomically thin oxide-based synapses. At a low bias voltage of 200 mV, the device is able to emulate synaptic functionalities under a pulse width of 500 ms of 455 nm.…”

“…Materials with decaying PPC are utilized for this purpose, where the poststimulus decaying photocurrent in optoelectronic synapses is likened to the postsynaptic current (PSC) generation observed in biological synapses during the information processing/memory formation process . In recent years, atomically thin semiconductors are being widely investigated for varied applications including artificial synaptic devices. − Such optoelectronic devices with PPC characteristics have been used to devise synapses functioning across the electromagnetic spectrum. − With time, there has been widespread application of such materials and their heterostructures to devise visible-active synaptic applications. ,, However, these devices often require high driving bias or additional stimuli to engineer/prolong their PPC property. , Metal oxide-based semiconductors form a coveted category of materials for optoelectronic synapses due to their superlative optoelectronic properties and well-established synthesis processes . Despite their high photocurrent generation and high mobility, their poor to absent response to visible wavelengths deems them unsuitable for visible-active synaptic applications. , In recent years, liquid metal printing has allowed the realization of many nonstratified metal oxides in ultrathin morphology with properties different from their bulk counterparts, thereby allowing the facile realization of large-scale 2D materials applicable for various semiconducting and conducting applications , and enabling the engineering and application of many such atomically thin LM-printed oxides for UV-active optoelectronic synapses. ,, However, there has not been much development in engineering these oxides for optoelectronic synaptic applications in the visible region.…”

“…15,17 In recent years, liquid metal printing has allowed the realization of many nonstratified metal oxides in ultrathin morphology with properties different from their bulk counterparts, thereby allowing the facile realization of largescale 2D materials applicable for various semiconducting and conducting applications 18,19 and enabling the engineering and application of many such atomically thin LM-printed oxides for UV-active optoelectronic synapses. 9,20,21 However, there has not been much development in engineering these oxides for optoelectronic synaptic applications in the visible region. In 2 O 3 , a well-established wide-band gap nonlayered TSO, has been known to show PPC characteristics upon exposure to UV radiation at low operational voltages.…”

Thickness-Dependent Room-Temperature Optoelectronic Gas Sensing Performances of 2D Nonlayered Indium Oxide Crystals from a Liquid Metal Printing Process

“…2D materials, consisting of a single or several atomic layers, such as graphene, black phosphorus (BP), and layered transition-metal dichalcogenides (TMDs), , are currently considered promising materials for room temperature NO 2 gas sensing application due to their high active surface, tunable electronic structure, as well as unique physicochemical properties. − While the high surface activity also results in the difficult desorption of gas molecules, thus resulting in long recovery times , or poor reversibility . Nevertheless, considering the excellent charge carrier mobility, electronic and optoelectronic properties of 2D materials, , photoexcitation is a viable and simple approach to facilitate full reversibility , and improve gas sensing responses simultaneously. − …”

“…10−12 While the high surface activity also results in the difficult desorption of gas molecules, thus resulting in long recovery times 13,14 or poor reversibility. 15 Nevertheless, considering the excellent charge carrier mobility, electronic and optoelectronic properties of 2D materials, 16,17 photoexcitation is a viable and simple approach to facilitate full reversibility 18,19 and improve gas sensing responses simultaneously. 20−22 Currently, the search for suitable optoelectronic gas sensing materials mainly focuses on 2D intrinsic layered materials, while metal oxides, the traditional category of gas-sensitive materials, are rarely seen with a layered structure.…”