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Platinum diselenide (PtSe2), a recently rediscovered two-dimensional transition metal dichalcogenide, has attracted immense attention in the optoelectronic field due to its tunable bandgap, ultrastability, and high electron mobility. However, the applications of PtSe2 photodetectors are seriously restricted by their low responsivity. In this work, a high-responsivity (5 × 104 A/W) PtSe2 photodetector is obtained by exploiting a photogating effect; this is induced by the hole-trapping states, which are attributed to Se vacancies. Moreover, a gate-tunable transition between the positive and negative photoconductances is observed under light illumination. A theoretical calculation based on the Boltzmann transport theory is performed to explain the carrier transport of PtSe2, considering the contributions of charged impurity, acoustic phonon, and polar optical phonon scattering.

Ti contact properties and their electrical contribution to an amorphous InGaZnO (a-IGZO) semiconductor-based thin film transistor (TFT) were investigated in terms of chemical, structural, and electrical considerations. TFT device parameters were quantitatively studied by a transmission line method. By comparing various a-IGZO TFT parameters with those of different Ag and Ti source/drain electrodes, Ti S/D contact with an a-IGZO channel was found to lead to a negative shift in VT (−Δ 0.52 V). This resulted in higher saturation mobility (8.48 cm2/Vs) of a-IGZO TFTs due to effective interfacial reaction between Ti and an a-IGZO semiconducting layer. Based on transmission electron microcopy, x-ray photoelectron depth profile analyses, and numerical calculation of TFT parameters, we suggest a possible Ti contact mechanism on semiconducting a-IGZO channel layers for TFTs.

We report on antireflective ZnSnO (ZTO)/Ag bilayer and ZTO/Ag/ZTO trilayer source/drain (S/D) electrodes for highly transparent ZTO channel-based thin film transistors (TFTs). Although both bilayer and trilayer films have a similar sheet resistance (3–5 Ω/sq), the ZTO/Ag bilayer is a more effective transparent S/D electrode for ZTO channel layer than the ZTO/Ag/ZTO trilayer S/D electrode, due to the direct contact of the Ag layer on the ZTO channel layer and a desirable oxide-metal-oxide multilayer structure for antireflection effects. ZTO channel-based all-transparent TFTs with ZTO/Ag bilayer S/D electrodes exhibited a saturation mobility of 4.54 cm2/Vs and a switching value (1.31 = V/decade), comparable to those of a ZTO channel-based TFT with metallic Ag S/D electrodes. This indicates that the antireflective ZTO/Ag bilayer is a promising transparent S/D electrode for use in all-transparent TFTs as a substitute for conventional opaque metal S/D electrodes.

An efficient three-dimensional (3D) nanostructure photoelectric device is presented. An Al-doped ZnO (AZO) coating was applied to lithography-free patterned Si nanopillars and spontaneously formed a radial heterojunction (n-AZO/p-Si) photodiode having a quality ideality factor of 1.64. A significantly enhanced photocurrent of 5.45 mA/cm2 was obtained from the 3D nanostructure relative to that of a planar substrate (1.1 mA/cm2). This enhancement is induced by enlargement of the light-active surface area and an anti-reflection effect. Due to the intermediate refractive index of AZO, the reflection was distinctively reduced in the air-Si system. It discusses an effective approach for realizing nanostructured photoelectric device.

In this report, ZnO single nanowire (NW)-based devices were fabricated on the same nanowire by e-beam lithography so that both sides had Ohmic contact and one side had Schottky contact. Information about the mechanism for low-power UV detection by these devices was unambiguously provided by I-V measurements. Adsorption and desorption of oxygen molecules at the NW surface are responsible for the UV detection by the device with Ohmic contacts on both sides. Barrier height modulations and interface states are responsible for UV detection by the device with Schottky contact on one side.

We investigated the transfer characteristics and the gate-bias stability of amorphous indium-gallium-zinc oxide thin-film transistors when the channel layer was exposed to hydrogen, oxygen, air, or vacuum at room temperature during measurements. The threshold voltage and the drain current were changed by the ambient atmospheres. The threshold voltage shift (ΔVth) under gate-bias stress was faster in hydrogen than in oxygen and vacuum. It is suggested that hydrogen exposure degrades the gate-bias stress stability due to surface accumulation layer creation. The characteristic trapping times, τ, in H2, O2, air, and vacuum were 5×103, 1.5×104, 2×104, and 6.3×104 s, respectively.

We have fabricated an ultrahigh-vacuum-processed, ordered, single-crystalline nanodot array. By mapping the magnetization of the nanodots with spin polarized scanning tunneling microscopy in the same chamber where they were grown, we are able to understand how the short-range order of the nanodot array is determined by the magnetostatic dipole interaction among neighboring nanodots. We also demonstrate tuning the magnetic interaction in the nanodot array by controlling those magnetic energies. Further magnetic simulations support the observed results consistently.

In this letter we have studied an influence of surface morphology on the optical property of vertically aligned ZnO nanorods. At low temperature the near band edge excitonic emission shows a strong dependence on surface morphology. A prominent and well resolved near band edge photoluminescence (PL) peak was obtained for nanowires with decreasing diameter and thus assigned due to the contributions to the optical properties of individual nanorods. Depending on surface morphology, the difference in low temperature PL property is attributed to the tailing of the density of states due to the potential fluctuations in randomly distributed intrinsic defects.

This letter reports the utility of using the sol-gel process for exploring the library of multicomponent ZnO-based oxides as an active layer of thin film transistors. We chose InGaZnO as a starting material and modulated the Ga content to examine the potential of this material. Increasing the Ga ratio from 0.1 to 1 brought about a dynamic shift in the electrical behavior from conductor to semiconductor. This exploratory work critically helped us fabricate a device with robust device performance (a mobility of 1∼2 cm2 V−1 s−1 for the 400 °C-sintered samples and 0.2 cm2 V−1 s−1 for the 300 °C-sintered samples).

A low-power ultrahigh-frequency-driven inductively coupled microplasma (ICMP) source equipped with dielectric-barrier discharge (DBD) was developed to realize a low-temperature and high-density plasma in fine quartz capillaries with inner diameters of less than 1.0 mm. A stable plasma was generated and its sustainability was independent of the gas flow rate. This plasma jet had a longer plume than that of a thermoelectron-enhanced microplasma jet, and time-resolved characterization suggested interactions between ICMP and DBD jets. By optical emission spectroscopy characterization, the gas temperature and electron density inside a capillary were estimated to be 400–1000 K and 1013–1014 cm−3, respectively.

Plasma with a gas temperature below room temperature is not yet fully understood although it is expected to be an attractive tool for applications to material processing. In the present work, gas-temperature-dependent generation of a cryoplasma jet was studied. So far, we have generated a helium cryoplasma jet (296–5K) under atmospheric pressure. At gas temperatures below 20K, the helium excimer, He2, was observed clearly from by optical emission spectroscopy.

Dielectric barrier discharges were generated under atmospheric pressure at temperatures ranging from room temperature down to 88K. The gas temperature of the plasma generated by the discharges was controlled by liquid nitrogen, and a mixture of helium and air was used as the discharge gas. We found that microdischarges exhibited temperature-dependent specific discharge patterns as the temperature decreased. This transition of discharge patterns was closely related to the change in the gap voltage at breakdown. A possible scenario that may explain the pattern of the transition of the microdischarges is discussed.

By inserting a very thin layer of Ag between two layers of amorphous indium zinc tin oxide (IZTO), we fabricated a highly flexible, low resistance, and highly transparent IZTO-Ag-IZTO multilayer electrode on a polyethylene terephthalate (PET) substrate. Due to surface plasmon resonance (SPR) effects and the ductility of the Ag layer, the IZTO-Ag-IZTO electrode exhibited a low sheet resistance of 4.99Ω∕sq. and a high transparency of 86% as well as superior flexibility despite the very thin thickness of the IZTO layer (30nm). It was found that the transition of the Ag layer from distinct islands to a continuous film occurred at a critical thickness (∼14nm). Continuity of the Ag film is very important for SPR in IZTO-Ag-IZTO electrode. The current density-voltage-luminance characteristics of flexible organic light emitting diodes (OLEDs) fabricated on IZTO-Ag-IZTO/PET were better than those of flexible OLEDs fabricated on an ITO/PET substrate due to the low sheet resistance and high work function of the IZTO.

We grew well-ordered arrays of ferroelectric Pb(Zr0.2Ti0.8)O3 (PZT) nanodots on a SrRuO3∕SrTiO3 substrate by pulsed laser deposition. A silicon nitride shadow mask with ordered holes was used for patterning of the PZT arrays. Each dot has a height of ∼15nm and a diameter of ∼120nm with a similar dome shape over a large area. The ferroelectric properties of individual PZT dots were investigated by piezoresponse force microscopy. A single dot could be polarized individually and the polarized state remained unrelaxed to ∼20min.

Cobalt–polypyrrole(PPy)–cobalt nanowires were fabricated electrochemically in single-wire form inside anodic aluminum oxide templates. These wires were isolated by dissolving the template with chromic acid. Grown cobalt segments at both ends reveal a polycrystalline structure of a hexagonal-closest-packed structure and their [001] directions are 16° off the wire axis. By patterning a gate on one side of the wire, field-effect transistors (FETs) were produced. The measured output and transfer characteristics are as good as or better than film FETs of PPy. The gain of the wire FET could be controlled with successive electrochemical doping of the PPy segment.

We present a device structure of SiO2∕SiN∕Al2O3 (SANOS). The use of a high-k dielectric material, specially Al2O3, in the blocking oxide concentrates the electric fields across the tunnel oxide and SiN, and releases it across the blocking oxide under program and erase mode. This effect leads to lower program and erase voltage as well as faster erase speed than the conventional SiO2∕SiN∕SiO2 (SONOS) device. Moreover, it is shown that the fast erase operation is performed even at a thicker tunnel oxide over 30A where the hole direct tunneling current through the tunnel oxide is reduced significantly and thus the SANOS device has the excellent bake retention.