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Multi-terminal memtransistors using polycrystalline monolayer molybdenum disulfide (MoS2) have recently emerged as novel synaptic devices. Due to the coexistence of disorder and strong Coulomb carrier-carrier interactions in MoS2, localization and delocalization of carriers can come into play successively upon the relative strength of disorder and interactions, which can be tuned by the Fermi level ( E F ). In this work, we show that the transition from trap-mediated to band-like transport leads to the resistive switching behavior in MoS2 memtransistors, which is driven by the E F shift arising from defect profile redistribution that is facilitated by grain boundaries. In the high resistance state, field-driven hopping conduction can be clearly observed in the high-field region (E > 0.05 MV/cm), whereas the linear dependence of l n (I / E) on the square root of the electric field, E 1 / 2 , suggests Poole–Frenkel emission in the low-field region (E ≤ 0.05 MV/cm). In the low resistance state, strong interactions prevailed and a substantial amount of thermally activated electrons are excited into the conduction band, leading to band-like transport. [ABSTRACT FROM AUTHOR]

The analog resistive switching (RS) characteristics in 2-D polycrystalline (poly-) molybdenum disulfide (MoS2) field-effect transistors (FETs) enable new electronic devices capable of emulating biological synaptic behaviors. In 2-D poly-materials, grain boundary (GB)-induced trap states are of major significance to RS behaviors. However, there is still a lack of appropriate compact models that capture accurate physical mechanisms. Therefore, we developed a surface potential-based compact model, based on the theories of the GB energy barrier and space charge limited current (SCLC). By calibrating to experimental data of MoS2, the physical parameters are extracted, and the model explains the scaling behaviors of channel lengths and grain sizes. Due to the electric-field-induced defect redistribution, the energy barrier modulation at a single-GB (e.g., intersecting GB) quantitatively matches the reported experiments. Moreover, the possible SCLC-based RS behavior is also investigated. Furthermore, we have optimized the set/reset process and simulated the postsynaptic current (PSC) with a tunable potentiation (or depression) process, and then the gate voltage dependence and statistical effects on RS and PSC have been investigated. Thus, this model provides important devices physics insights of 2-D poly-materials and it guides device design, fabrication, and material engineering, to meet the requirements of the future neuromorphic computing application. [ABSTRACT FROM AUTHOR]

Realization of memristors capable of storing and processing data on flexible substrates is a key enabling technology toward "system‐on‐plastics". Recent advancements in printing techniques show enormous potential to overcome the major challenges of the current manufacturing processes that require high temperature and planar topography, which may radically change the system integration approach on flexible substrates. However, fully printed memristors are yet to be successfully demonstrated due to the lack of a robust printable switching medium and a reliable printing process. An aerosol‐jet‐printed Ag/MoS2/Ag memristor is realized in a cross‐bar structure by developing a scalable and low temperature printing technique utilizing a functional molybdenum disulfide (MoS2) ink platform. The fully printed devices exhibit an ultra‐low switching voltage (0.18 V), a high switching ratio (107), a wide range of tuneable resistance states (10–1010 Ω) for multi‐bit data storage, and a low standby power consumption of 1 fW and a switching energy of 4.5 fJ per transition set. Moreover, the MoS2 memristor exhibits both volatile and non‐volatile resistive switching behavior by controlling the current compliance levels, which efficiently mimic the short‐term and long‐term plasticity of biological synapses, demonstrating its potential to enable energy‐efficient artificial neuromorphic computing. [ABSTRACT FROM AUTHOR]

High-resolution x -ray photoelectron spectroscopy (XPS) was employed to characterize the energy band alignment between TiO 2 /multilayer (ML)-MoS 2 . The TiO 2 film and ML-MoS 2 film was grown by an atomic layer deposition (ALD) and chemical vapor deposition (CVD), respectively. The effect of CHF 3 plasma treatment on the band alignment between TiO 2 /ML-MoS 2 was evaluated. It was found that the valence band offset (VBO) and a conduction band offset (CBO) of TiO 2 /ML-MoS 2 interface was changed from 2.28 eV to 2.51 eV, and from 0.28 eV to 0.51 eV, respectively for the sample with CHF 3 plasma treatment. With the CHF 3 plasma treatment, the down-shift of Mo 3d core level binding energy results in a bend-up of energy potential on the MoS 2 side, leading to 0.23 eV ΔE C difference between the control and the sample with CHF 3 plasma treatment, which is caused by the interfacial layer in rich of F element. The physics details of the band alignment at TiO 2 /ML-MoS 2 interface will provide a guide for the MoS 2 based electronic device design. [ABSTRACT FROM AUTHOR]

The energy band alignment between Al 2 O 3 /multilayer (ML)-MoS 2 was characterized using high-resolution x -ray photoelectron spectroscopy (XPS). The Al 2 O 3 was deposited using an atomic layer deposition (ALD) tool. A valence band offset of 4.10 eV and a conduction band offset of 3.41 eV were obtained across the ALD-Al 2 O 3 /ML-MoS 2 interface. For comparison, the valence band offset and a conduction band offset were also obtained for ALD-SiO 2 /ML-MoS 2 interface. It was found out that ALD-Al 2 O 3 /ML-MoS 2 interface has a larger conduction band offset, compared to that of ALD-SiO 2 /ML-MoS 2 interface, which indicate ALD-Al 2 O 3 served as the gate dielectric for n-type ML-MoS 2 based field effect transistors has advantage over ALD-SiO 2 in term of suppressing the gate leakage current. [ABSTRACT FROM AUTHOR]