An Artificial Neural Network Based on Oxide Synaptic Transistor for Accurate and Robust Image Recognition.

Synaptic transistors with low-temperature, solution-processed dielectric films have demonstrated programmable conductance, and therefore potential applications in hardware artificial neural networks for recognizing noisy images. Here, we engineered AlOx/InOx synaptic transistors via a solution process to instantiate neural networks. The transistors show long-term potentiation under appropriate gate voltage pulses. The artificial neural network, consisting of one input layer and one output layer, was constructed using 9 × 3 synaptic transistors. By programming the calculated weight, the hardware network can recognize 3 × 3 pixel images of characters z, v and n with a high accuracy of 85%, even with 40% noise. This work demonstrates that metal-oxide transistors, which exhibit significant long-term potentiation of conductance, can be used for the accurate recognition of noisy images.

Understanding Quasi-Static and Dynamic Characteristics of Organic Ferroelectric Field Effect Transistors.

Leveraging poly(vinylidene fluoride-trifluoroethylene) [(PVDF-TrFE)] as the dielectric, we fabricated organic ferroelectric field-effect transistors (OFe-FETs). These devices demonstrate quasi-static transfer characteristics that include a hysteresis window alongside transient phenomena that bear resemblance to synaptic plasticity-encapsulating excitatory postsynaptic current (EPSC) as well as both short-term and long-term potentiation (STP/LTP). We also explore and elucidate other aspects such as the subthreshold swing and the hysteresis window under dynamic state by varying the pace of voltage sweeps. In addition, we developed an analytical model that describes the electrical properties of OFe-FETs, which melds an empirical formula for ferroelectric polarization with a compact model. This model agrees well with the experimental data concerning quasi-static transfer characteristics, potentially serving as a quantitative tool to improve the understanding and design of OFe-FETs.

How Materials and Device Factors Determine the Performance: A Unified Solution for Transistors with Nontrivial Gates and Transistor-Diode Hybrid Integration.

Advanced field-effect transistors (FETs) with nontrivial gates (e.g., offset-gates, mid-gates, split-gates, or multi-gates) or hybrid integrations (e.g., with diodes, photodetectors, or field-emitters) have been extensively developed in pursuit for the "More-than-Moore" demand. But understanding their conduction mechanisms and predicting current-voltage relations is rather difficult due to countless combinations of materials and device factors. Here, it is shown that they could be understood within the same physical picture, i.e., charge transport from gated to nongated semiconductors. One proposes an indicator based on material and device factors for characterizing the transport and derives a unified and simplified solution for describing the current-voltage relations, current saturation, channel potentials, and drift field. It is verified by simulations and experiments of different types of devices with varied materials and device factors, employing organic, oxide, nanomaterial semiconductors in transistors or hybrid integrations. The concise and unified solution provides general rules for quick understanding and designing of these complex, innovative devices.

Evidence for Pseudocapacitance and Faradaic Charge Transfer in High-Mobility Thin-Film Transistors with Solution-Processed Oxide Dielectrics.

In developing low-power electronics, low-voltage transistors have been intensively investigated. One of the most important findings is that some high-k oxide gate dielectrics can lead to remarkable enhancement of apparent mobility in thin-film transistors (TFTs), which is not clearly understood. Here, we investigate InOx TFTs with solution-processed AlOx dielectrics. At very low frequencies (<1 Hz), the AlOx films feature strong voltage-dependent capacitance. Also, cyclic voltammograms show clear features of surface-controlled Faradaic charge transfer. The two independent experiments both point to the formation of pseudocapacitance, which is similar to the mechanism behind some supercapacitors. A physical model including charge transfer is established to describe ion distribution. The charge transfer is probably related to residual hydrogens, as revealed by secondary-ion mass spectroscopy. The results provide direct evidence of the formation of pseudocapacitance in TFTs with high apparent mobilities and advance the understanding of mechanisms, measurements, and applications of such TFTs for low-power electronics.

CdS-Nanowires Flexible Photo-detector with Ag-Nanowires Electrode Based on Non-transfer Process.

In this study, UV-visible flexible resistivity-type photo-detectors were demonstrated with CdS-nanowires (NWs) percolation network channel and Ag-NWs percolation network electrode. The devices were fabricated on Mixed Cellulose Esters (MCE) membrane using a lithographic filtration method combined with a facile non-transfer process. The photo-detectors demonstrated strong adhesion, fast response time, fast decay time, and high photo sensitivity. The high performance could be attributed to the high quality single crystalline CdS-NWs, encapsulation of NWs in MCE matrix and excellent interconnection of the NWs. Furthermore, the sensing performance was maintained even the device was bent at an angle of 90°. This research may pave the way for the facile fabrication of flexible photo-detectors with high performances.