Artificial synapses based on 2D MoS2 memtransistors have recently attracted considerable attention as a promising device architecture for complex neuromorphic systems. However, previous memtransistor devices occasionally cause uncontrollable analog switching and unreliable synaptic plasticity due to random variations in the field‐induced defect migration. Herein, a highly reliable 2D MoS2/Nb2O5 heterostructure memtransistor device is demonstrated, in which the Nb2O5 interlayer thickness is a critical material parameter to induce and tune analog switching characteristics of the 2D MoS2. Ultraviolet photoelectron spectroscopy and photoluminescence analyses reveal that the Schottky barrier height at the 2D channel–electrode junction of the MoS2/Nb2O5 heterostructure films is increased, leading to more effective contact barrier modulation and allowing more reliable resistive switching. The 2D/oxide memtransistors attain dual‐terminal (drain and gate) stimulated heterosynaptic plasticity and highly precise multi‐states. In addition, the memtransistor devices show an extremely low power consumption of ≈6 pJ and reliable potentiation/depression endurance characteristics over 2000 pulses. A high pattern recognition accuracy of ≈94.2% is finally achieved from the synaptic plasticity modulated by the drain pulse configuration using an image pattern recognition simulation. Thus, the novel 2D/oxide memtransistor makes a potential neuromorphic circuitry more flexible and energy‐efficient, promoting the development of more advanced neuromorphic systems.

A growth technique to directly prepare two-dimensional (2D) materials onto conventional semiconductor substrates, enabling low-temperature, high-throughput, and large-area capability, is needed to realize competitive 2D transition-metal dichalcogenide (TMD)/three-dimensional (3D) semiconductor heterojunction devices. Therefore, we herein successfully developed an atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) technique, which could grow MoS2 and WS2 multilayers directly onto PET flexible substrate as well as 4-in. Si substrates at temperatures of <200 °C. The as-fabricated MoS2/Si and WS2/Si heterojunctions exhibited large and fast photocurrent responses under illumination of a green light. The measured photocurrent was linearly proportional to the laser power, indicating that trapping and detrapping of the photogenerated carriers at defect states could not significantly suppress the collection of photocarriers. All the results demonstrated that our AP-PECVD method could produce high-quality TMD/Si 2D–3D heterojunctions for optoelectronic applications.

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Wide band gap oxide materials with additional infrared (IR) photosensing have rarely been reported because of the lack of the IR-associated sub band gap absorption. In this work, we report that the insertion of a thin aluminum oxide (Al2O3) layer between the Al electrode and indium gallium zinc oxide (IGZO) channel, deposited by atomic layer deposition, enables the material to absorb 850 nm IR light as well as light at visible wavelengths (400 and 530 nm). UV–visible absorption and photoluminescence measurements showed that the Al2O3/IGZO-stacked channel layers could induce additional IR absorption and, consequently, IR-excited charge carriers owing to sub-gap doping within the IGZO band gap. Notably, this approach provides the synergetic effect of enabling IR detection as well as improving the contact properties in the IGZO transistor. Furthermore, the clear dynamic photoswitching behavior was observed only for the Al2O3/IGZO transistor device, revealing a photocurrent 50 times higher than the device containing only IGZO. Thus, the simple approach of engineering the interface of wide band gap oxide materials made it possible to introduce unexpected dual-band gap photosensing characteristics, thereby extending the range of photonic applications of these materials.