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In this study, a laterally coupled device composed of a photodiode and a Si nanowires-field-effect transistor (NWs-FET) is constructed on a plastic substrate and the coupled device is characterized. The photodiode is made of p-type Si NWs and an n-type ZnO film. The Si NWs-FET is connected electrically to the photodiode in order to enhance the latter's photocurrent efficiency by adjusting the gate voltage of the FET. When the FET is switched on by biasing a gate voltage of -9 V, the photocurrent efficiency of the photodiode is three times higher than that when the FET is switched off by biasing a gate voltage of 0 V. [ABSTRACT FROM AUTHOR]

In this study, Si-nanoparticle(NP)/Si-nanowire(NW)-based field-effect transistors (FETs) with a top-gate geometry were fabricated and characterized. In these FETs, Si NPs were embedded as localized trap sites in Al2O3 top-gate layers coated on Si NW channels. Drain current versus drain voltage ( I DS− V DS) and drain current versus gate voltage ( I DS− V GS) were measured for the Si NP/Si NW-based FETs to investigate their electrical and memory characteristics. The Si NW channels were depleted at V GS = 9 V, indicating that the devices functioned as p-type depletion-mode FETs. The top-gate Si NW-based FETs decorated with Si NPs show counterclockwise hysteresis loops in the I DS− V GS curves, revealing their significant charge storage effect. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this paper, we describe the feedback and tunneling operations of a dual top gate field-effect transistor (FET) with a p+-i-n+ doped silicon nanowire channel. The transistor functions selectively in either a feedback FET (FBFET) or a tunneling FET mode by modulating the source-to-drain voltage, and it features an outstanding subthreshold swing characteristic of 6.15 mV dec–1 with an on/off current ratio (Ion/Ioff) of approximately 106 in the feedback operating mode and of 41.3 mV dec–1 with Ion/Ioff of ∼107 in the tunneling operating mode. Moreover, our device in the FBFET operation mode has memory characteristics with a retention time of 104 s and a program/erase endurance up to 103 cycles owing to the positive feedback loop in the channel region. This study demonstrates the promising potential of our devices in the development of multifunctional electronics. [ABSTRACT FROM AUTHOR]

In this study, we propose a simple method for obtaining the thermal conductivity of silicon nanowires (SiNWs) embedded on a thermoelectric platform. The approximation of the heat flux in SiNWs with temperature differences enables the determination of thermal conductivity. Using this method, the thermal conductivities of our n- and p-type SiNWs are found to be 18.06  ±  0.12 and 20.29  ±  0.77 W m−1 · K−1, respectively. The atomic weight of arsenic ions in the n-type SiNWs is responsible for a lower thermal conductivity than that of boron ions in the p-type SiNWs. Our results demonstrate that this simple method is capable of measuring the thermal conductivity of thermoelectric nanomaterials embedded on thermoelectric devices. [ABSTRACT FROM AUTHOR]

We construct a flexible pn heterostructured photodiode using a CdTe nanoparticle thin film and a single ZnO nanowire (NW) on a plastic substrate. The photocurrent characteristics of the flexible photodiode are examined under illumination with 325 nm wavelength light and the photocurrent efficiencies at bias voltages of +- 2.5 V are estimated to be 8.0 and 2.1 uA W [?] 1 under forward and reverse bias conditions, respectively. The photocurrent generation of the pn heterostructured photodiode is dominantly associated with the transport of the photogenerated charge carriers in the single ZnO NW. Furthermore, the operations of our flexible photodiode are investigated in the upwardly and downwardly bent states, as well as in the flat state. [ABSTRACT FROM AUTHOR]

Electrically driven lasing was demonstrated in light-emitting devices composed of n-ZnO and p-Si nanowires (NWs). The ZnO NWs were synthesized by thermal chemical vapor deposition and the Si NWs were formed by crystallographic wet etching of a Si wafer. The p-n heterojunction devices were constructed using the NWs by the direct transfer and dielectrophoresis methods. At an excitation current of 2 uA, the electroluminescence spectrum showed lasing behavior, and this phenomenon was explained by the ZnO-nanostructure-related cavity property. [ABSTRACT FROM AUTHOR]

A technique to implement silicon nanowire (SiNW)-based tunneling field-effect transistors (TFETs) on flexible plastic substrates is developed for the first time. The p-i-n configured Si NWs are obtained from an Si wafer using a conventional top-down CMOS-compatible technology, and they are then transferred onto the plastic substrate. Based on gate-controlled band-to-band tunneling (BTBT) as their working principle, the SiNW-based TFETs show normal p-channel switching behavior with a threshold voltage of [?]1.86 V and a subthreshold swing of 827 mV/dec. In addition, ambipolar conduction is observed due to the presence of the BTBT between the heavily doped p+ drain and n+ channel regions, indicating that our TFETs can operate in the n-channel mode as well. Furthermore, the BTBT generation rates for both the p-channel and n-channel operating modes are nearly independent of the bending state (strain = 0.8%) of the plastic substrate. [ABSTRACT FROM AUTHOR]

The transfer of charge carriers, photogenerated in nanoparticles (NPs), into a single nanowire (NW) is demonstrated in this study by conducting a careful comparison of the optoelectronic characteristics of a ZnO NW with ZnO NPs attached to its surface, a bare ZnO NW and a film of close-packed ZnO NPs. Under the illumination of an above-gap light, the photocurrent taken from the NW with the NPs is remarkably higher in magnitude than that obtained from the bare NW, although the photocurrent is substantially lower for the close-packed NPs. The presence of the absorption band of the NPs in the photoresponse spectrum taken from the NW with the NPs reveals that the transfer of the charge carriers photogenerated in the NPs into the NW dramatically enhances the magnitude of the photocurrent flowing in this NW. Nevertheless, during the transfer, the charge carriers experience trapping and detrapping at the interfaces of the NPs and the NW. [ABSTRACT FROM AUTHOR]

Omega-shaped-gate (OSG) nanowire-based field effect transistors (FETs) have attracted a great deal of attention recently, because theoretical simulations predicted that they should have a higher device performance than nanowire-based FETs with other gate geometries. OSG FETs with channels composed of ZnO nanowires were successfully fabricated in this study using photolithographic processes. In the OSG FETs fabricated on oxidized Si substrates, the channels composed of ZnO nanowires with diameters of about 110 nm are coated with Al2O3 using atomic layer deposition, which surrounds the channels and acts as a gate dielectric. About 80% of the surfaces of the nanowires coated with Al2O3 are covered with the gate metal to form OSG FETs. A representative OSG FET fabricated in this study exhibits a mobility of 30.2 cm2/ (V s), a peak transconductance of 0.4 μS (Vg = −2.2 V), and an Ion/Ioff ratio of 107. To the best of our knowledge, the value of the Ion/Ioff ratio obtained from this OSG FET is higher than that of any of the previously reported nanowire-based FETs. Its mobility, peak transconductance, and Ion/Ioff ratio are remarkably enhanced by 3.5, 32, and 106 times, respectively, compared with a back-gate FET with the same ZnO nanowire channel as utilized in the OSG FET. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we demonstrate the photogating effects of p-type HgTe nanoparticles (NPs) on an n-type ZnO nanowire (NW). The photogating effects are due to the charge separation of the charge carriers photogenerated in the NPs under illumination and the subsequent accumulation of the photogenerated electrons in the pn junction of the NPs and the NW. The presence of the electrons in the junction reduces the current in the ZnO NW. The photogating effects are proved by the different photocurrent behavior of the ZnO NW to which the HgTe NPs are attached from that of a bare ZnO NW. In addition, the dependence of the photogating effects on the power of the incident light is discussed. [Copyright &y& Elsevier]