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• Prominent behaviors such as EPSC, PPF, and SFPD are successfully simulated with power consumption as low as 22 pJ. • Owning to its good short-term (STP) and tunable amplitude-frequency characteristics, the as-constructed device can function as a biomimetic high-pass filter for picture edge detection. • After photoelectric-synergistic modulation, the high synaptic weights enable the device to simulate complex neural learning rules for neuromorphic applications, including gesture recognition, image perception in the visual system and classically conditioned reflexes. The development of high-performance neuromorphic phototransistors is of paramount importance for image perception and depth memory learning. Here, based on metal-oxide heterojunction architecture, artificial synaptic phototransistors with synaptic plasticity have been achieved, demonstrating an artificial synapse that integrates central and optic nerve functions. Thanks to the sensitive light-detection properties, the optical power consumption of such photonic artificial synapses can be as low as 22 pico-joules, which is extremely competitive compared with other pure metal oxide photoelectric synapses ever reported. What is more, owing to its good short-term (STP) and tunable amplitude-frequency characteristics, the as-constructed device can function as a biomimetic high-pass filter for picture edge detection. Dual-mode synaptic modulation has been performed, combining photonic pulse with gate voltage stimulus. After photoelectric-synergistic modulation, the high synaptic weights enable the device to simulate complex neural learning rules for neuromorphic applications, including gesture recognition, image perception in the visual system, and classically conditioned reflexes. These results suggest that the current oxide-based heterojunction architecture displays potential application in future multifunction neuromorphic devices and systems. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hf-doped ZnO films with lower V O density were deposited via ALD method. • The annealing temperature was adjusted to obtain better interface characteristics. • The as-fabricated transistor owns the high field-effect mobility of 52.39 cm2/Vs. • The V TH shift of the transistor under PBST/NBST is as low as 0.957 V and 0.273 V. • The interface improvement mechanism was proposed based on phase transition theory. ZnO-based thin film transistors (TFTs) with high bias stability are challenging due to the intrinsic defects and overhigh interface trap density. In this work, we fabricated Hf-doped ZnO films with different cycle ratio of Zn/Hf via atomic layer deposition and subsequent annealing treatment. The results show that the cycle ratio of Zn/Hf is optimized to be 10:1, and the corresponding atomic ratio is 2.24%. The threshold voltage and subthreshold swing of the devices are improved as the annealing temperature increases, owning to the decrease of the oxygen vacancies and interface trap density. Furthermore, we developed Hf-doped ZnO TFT with high bias stability by introducing HfO 2 intermediate layer between the active layer and SiO 2 dielectric layer, and the shift of threshold voltage is as low as -0.273 V, showing high bias stability. Also, the device has the high field-effective mobility of 52.4 cm2/Vs, low subthreshold swing of 0.68 V/dec and high I on /I off of 3.6 × 108. The results indicate a promising fabrication method for high-performance ZnO-based TFTs, which may be applied in logic circuits, radio frequency identification and so on. [Display omitted] [ABSTRACT FROM AUTHOR]

• Fully solution-derived GQDs-IGZO TFTs based on ZrO x as gate dielectrics have been achieved. • GQDs-IGZO TFTs devices with optimized doping content have demonstrated improved performances, including a μ FE of 35.91 cm2 V–1 s–1, a higher I ON / I OFF of 5.04 × 108, a smaller subthreshold swing (SS) of 0.11 V dec–1 and a smaller interfacial trap states of 1.57 × 1012 cm−2. • Resistor-loaded unipolar inverter based on GQDs-IGZO/ZrO x has been integrated, demonstrating good dynamic behavior and a high gain of 9.3. • LFN characteristics of GQDs-IGZO/ZrO x TFTs have suggested that the fluctuations in mobility are the noise source. This work presents solution-processed high-performance graphene quantum dots (GQDs) decorated amorphous InGaZnO (α-IGZO) thin-film transistors (TFTs) based on ZrO x as gate dielectrics. Compare with pure IGZO TFTs, GQDs-modified α-IGZO TFTs devices with optimized doping content have demonstrated better performances, including a larger field-effect mobility (μ FE) of 35.91 cm2 V–1 s–1, a higher on/off current ratio (I ON / I OFF) of 5.04 × 108, a smaller subthreshold swing (SS) of 0.11 V dec–1 and a smaller interfacial trap states (D it , 1.57 × 1012 cm−2). Moreover, the GQDs-doped IGZO TFTs with a doping concentration of 0.5 mg ml–1 have shown excellent stability under bias stress and illumination stress conditions. To demonstrate the potential applications of α-IGZO TFTs in logic circuits, a resistor-loaded unipolar inverter based on GQDs-IGZO/ZrO x has been integrated, demonstrating good dynamic behavior and a high gain of 9.3. Low-frequency noise (LFN) characteristics of GQDs-IGZO/ZrO x TFTs have suggested that the fluctuations in mobility are the noise source. Based on all the experimental findings, it can be concluded that solution-processed GQDs-IGZO/ZrO x TFT may envision promising applications in optoelectronics. [Display omitted] [ABSTRACT FROM AUTHOR]

Reactive sputtered boron-doped zinc oxide (BZO) film was deposited from argon, hydrogen and boron gas mixture. The reactive sputtering technique provides us the flexibility of changing the boron concentration in the produced films by using the same intrinsic zinc oxide target. Textured surface was obtained in the as-deposited films. The surface morphology and the opto-electronic properties of the films can be controlled by simply varying the gas concentration ratio. By varying the gas concentration ratio, the best obtained resistivity ∼ 6.51 × 10−4 Ω-cm, mobility ∼ 19.05 cm2 V-1 s-1 and sheet resistance ∼ 7.23 Ω/□ were obtained. At lower wavelength of light, the response of the deposited films improves with the increase of boron in the gas mixture and the overall transmission in the wavelength region 350−1100 nm of all the films are >85 %. We also fabricated amorphous silicon (a-Si) thin film solar cell on the best obtained BZO layers. The overall efficiency of the a-Si solar cell is 8.14 %, found on optimized BZO layer. [ABSTRACT FROM AUTHOR]

In this work, a non-toxic and environmentally friendly aqueous-solution-based method has been adopted to prepare gadolinium-doped hafnium oxide (HfO 2) gate dielectric thin films. By adjusting the gadolinium (Gd) doping concentration, the oxygen vacancy content, band offset, interface trap density, and dielectric constant of HfGdO x (HGO) thin films have been optimized. Results have confirmed that HGO thin films with Gd doping ratio of 15 at.% have demonstrated appropriate dielectric constant of 27.1 and lower leakage current density of 5.8 × 10−9 A cm-2. Amorphous indium-gallium-zinc oxide (α-IGZO) thin film transistors (TFTs) based on HGO thin film (Gd: 15 at.%) as gate dielectric layer have exhibited excellent electrical performance, such as larger saturated carrier mobility (μ sat) of 20.1 cm2 V-1 S-1, high on/off current ratio (I on / I off) of ∼108, smaller sub-threshold swing (SS) of 0.07 V decade-1, and a negligible threshold voltage shift (△ V TH) of 0.08 V under positive bias stress (PBS) for 7200 s. To confirm its potential application in logic circuit, a resistor-loaded inverter based on HGO/α-IGZO TFTs has been constructed. A high voltage gain of 19.8 and stable full swing characteristics have been detected. As a result, it can be concluded that aqueous-solution-driven HGO dielectrics have potential application in high resolution flat panel displays and ultra-large-scale integrated logic circuits. [ABSTRACT FROM AUTHOR]

Direct-patterned Cu-based conductive electrodes were printed through electrohydodynamic (EHD) jet printing via cone-jet mode. The introduction of a capping agent in the synthesis of the Cu ink limited excessive conductivity, which enabled the pristine Cu ink to achieve the various printing modes of EHD jet printing: dripping, micro-dripping, cone-jet, and multi-jet. We also obtained optimal printing conditions by adjusting the viscosity by adding poly(ethylene oxide) (PEO) to the pristine Cu inks, resulting in well-defined printing patterns. The optimized PEO content in the ink was determined to be ∼10 wt%, which gave us a stable cone-jet mode and well-defined Cu/PEO composite electrode lines with sharp edges. We utilized the Cu/PEO composite electrode lines as source and drain and a triisopropylsilylethynyl (TIPS)–pentacene/PS blend as the active layer for bottom-gate bottom-contact organic field-effect transistors (OFETs). The resulting devices exhibited an average field-effect mobility (μ FET), threshold voltage (V th), and on/off current ratio (I on /I off) of 0.253 cm2/V, 0.253 V, and ∼106, respectively. [ABSTRACT FROM AUTHOR]