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In this study, we investigate the influence of an overlap between the gate and source/drain regions of a-Si:H thin film transistors (TFTs) on their electrical characteristics under tensile or compressive strain through experiment and mechanical simulation. The strain distribution in the a-Si:H TFT for a bending radius of 2 mm reveals that the strain at both ends of the TFT is ten times larger than that at the source-drain current path. The overlap lowers the stress sustained by the TFT in the region comprised between the channel and the gate insulator; therefore, TFTs with the overlap operate even at a tensile strain of 2.54%. In particular, the overlap is remarkably effective on relaxing the stress sustained in the interface between the gate insulator and the gate electrode, consequently improving the electrical stability of the bent TFT.

In this study, we report the electrical and mechanical characteristics of fully transparent indium zinc oxide (IZO) thin-film transistors (TFTs) fabricated on stress-relieving bendable substrates. An IZO TFT on a stress-relieving substrate can operate normally at a bending radius of 6 mm, while an IZO TFT on a normal plastic substrate fails to operate normally at a bending radius of 15 mm. A plastic island with high Young's modulus embedded on a soft elastomer layer with low Young's modulus plays the role of a stress-relieving substrate for the operation of the bent IZO TFT. The stress and strain distributions over the IZO TFT will be analyzed in detail in this paper.

ZnO nanorods were grown on SiO2/Si substrates by a sol-gel method at low temperatures of around T=95 °C. The diameters and the lengths of ZnO nanorods increased at high concentrations of zinc nitrate hexahydrate and methenamine solution. Current–voltage characteristics of the ZnO nanorods network followed a typical nonlinear behavior with significant photoresponse below λ

ZnO nanowires were grown between two Au electrodes on an Al2O3-deposited Si wafer. Photoresponse, photoresponse spectrum, and current–voltage (I–V) studies were performed for the investigation into photoconduction mechanism in these nanowires. The photoresponse of the nanowires under the continuous illumination of light with above- or below-gap energies was slow, which indicates that photocurrent in the nanowires is surface-related rather than bulk-related. The photoresponse spectrum represents the above- and below-gap absorption bands for the photocurrents. The I–V characteristics under the illumination of the above-gap light are ohmic, but the characteristics under the illumination of the below-gap light are Schottky. This observation indicates that the above-gap light lowers the potential barrier built in the contact between the ZnO nanowires and electrodes, but that the below-gap light does not lower the potential barrier.

Photoluminescence, absorption, and photocurrent measurements were made for a hybrid system of 1-thioglycerol-capped HgTe nanoparticles synthesized by colloidal method to investigate the photocurrent mechanism in this hybrid system. Absorption and photoluminescence spectra taken for the capped HgTe nanoparticles reveal strong exciton peaks in the near-infrared wavelength range. The wavelength dependence of the photocurrent for these capped nanoparticles is very close to that of the absorption spectrum. For the photocurrent mechanism of the hybrid system, on the basis of our experimental results and energy diagram for the 1-thioglycerol-capped HgTe nanoparticles, it is suggested in this letter that holes among electron-hole pairs created by incident photons in the HgTe nanoparticles are transferred to capping 1-thioglycerol while electrons are strongly confined in these nanoparticles and that the holes contribute to the photocurrent flowing in the medium of 1-thioglycerol.

Nitrogen-doped gallium phosphide nanobelts were directly synthesized via a sublimation of ball-milled powders under ammonia flow. The average width of the nanobelts is 300 nm and the thickness is about 1/10 of the width. They consist of single-crystalline zinc blende structure crystal with the [111] direction parallel to the belt axis. Electron energy-loss spectroscopy reveals that the nitrogen doping occurs mainly in the surface region. Photoluminescence shows the typical isoelectronic bound exciton peaks in the range of 2.11–2.25 eV, suggesting a concentration of ∼1018 cm−3 nitrogen atoms.

The 1.54 μm Er3+ photoluminescence excitation (PLE) and photoluminescence (PL) spectra of erbium-doped silicon-rich silicon oxide (SRSO) are investigated. Between 350 and 820 nm, PLE spectra are broad and featureless, and the PL spectra are independent of the excitation wavelengths. The results indicate that in erbium-doped SRSO, the Er3+ luminescence is dominated by a single class of Er sites with a strong coupling to all the carriers in the silicon nanograins.

In this letter, we report the electrical and optical characteristics of p-channel In0.13Ga0.87As double heterojunction pseudomorphic modulation-doped field effect transistor (MODFET) structure grown by gas source molecular beam epitaxy. The Hall mobility and the density of 2-DHGs (two-dimensional hole gases) in the pseudomorphic In0.13Ga0.87As channel were measured to be 250 cm2/V s and 1.9×1012 cm−2 at 300 K, and 5800 cm2/V s and 1.5×1012 cm−2 at 23 K, respectively. The fabricated p-channel MODFET shows a good mobility property which is due to high valence band discontinuity of InGaP/GaAs/InGaAs double barriers. The peak energy in the photoluminescence spectrum from the p-channel pseudomorphic MODFET structure was found to be 1.4 eV (λ=881 nm). The photoresponsivity with this modified pseudomorphic MODFET structure shows outstandingly better than that of a pin photodiode, particularly at low incident optical power.

The photoluminescence spectrum of undoped epitaxial wurtzite GaN layers on sapphire was measured for applied hydrostatic pressures up to 73 kbar at 9 K and up to 62 kbar at 300 K. The pressure dependences of the I2 exciton recombination line and the ‘‘yellow’’ band (2.2 eV band at ambient pressure) were examined at 9 and 300 K, and the series of donor‐acceptor‐pair emission lines was analyzed at 9 K. From the I2 lines, it was found that the band gap increases with pressure by 4.4±0.1 meV/kbar at 9 K and 4.7±0.1 meV/kbar at 300 K.

We investigate the electroluminescence (EL) characteristics of a hybrid light-emitting diode (HyLED) with an emissive layer comprised of CdSe/Cd/ZnS core-shell nanoparticles (NPs) embedded in poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) on a plastic substrate. The EL characteristics change dramatically with increasing of the biased voltage. At low voltages, recombination of electrons and holes occurs only in the PFO film because of poor charge transfer in the PFO-CdSe/Cd/ZnS NPs composite film, while the color of the light-emitting from the HyLED changes from blue to red as the biased voltage increases from 7.5 to 17.5 V. We examine and discuss the mechanism of this color tunability.

We have investigated the effect of the temperature dependency on the device stability of pristine ZnO nanowires (NWs) field effect transistor (FET). Pristine ZnO NW FET shows a large threshold voltage (Vth) shift by 6.5 V after increasing the measured temperature from 323 to 363 K. This large shift in Vth is mainly due to thermally activated process. Thermally activated electrons from the deep level trap site can be free carriers which results in the shift in Vth in negative direction. Also, activation energy of ZnO NW FET is derived to be about 1.432 eV based on thermally activated Arrhenius model.

Silver doped zinc oxide nanowires (NWs) were synthesized on (0001) sapphire substrate by hot-walled pulsed laser deposition. Both enhancement mode and depletion mode NW field effect transistors (FETs) were fabricated. The shift of threshold voltage of silver doped zinc oxide NW FET was observed from 2.45 to −3.2 V depending on the diameter of NWs without any significant changes of the subthreshold swing, carrier concentration, and on/off ratios. We demonstrate that the transfer characteristics of silver doped zinc oxide NW FETs were closely related with the size of NW diameter and control the shift of threshold voltage.

We demonstrate a pn heterojunction diode constructed with a n-type ZnO nanowire (NW) and a p-type HgTe nanoparticle (NP) thin film on a SiO2/p-Si substrate. For the pn heterojunction diode, the rectifying characteristics of both the dark current and the photocurrent excited by 633 nm wavelength light were observed, but the photocurrent excited by 325 nm wavelength light possesses Ohmic characteristics. The optoelectronic characteristics of the pn heterojunction diode were compared with those of the ZnO NW and HgTe NP thin film composing it.

Sintered HgTe nanocrystal-based thin-film transistors (TFTs) with bottom- and top-gate geometries were fabricated at a temperature of 150°C by spin coating in this work. The SiO2 bottom- and Al2O3 top-gate field-effect TFTs with p channels composed of sintered HgTe nanocrystals exhibit high carrier mobilities of 0.82 and 2.38cm2∕Vs, respectively. The operating gate voltages for the top-gate transistor with an Al2O3 dielectric layer are actually lower, compared with the SiO2 bottom-gate transistor. The electrical characteristics of these TFTs are discussed in more detail in this letter.