PbS Nanowire Research Articles

Gate-tunable superconducting quantum interference devices of PbS nanowires

We report on the fabrication and electrical transport properties of gate-tunable superconducting quantum interference devices (SQUIDs), made from a semiconducting PbS nanowire contacted with PbIn superconducting electrodes. With a magnetic field applied perpendicular to the plane of the nanohybrid SQUID, periodic oscillations of the critical current due to the flux quantization in SQUID are observed up to T = 4.0 K. A nonsinusoidal current–phase relationship is obtained as a function of temperature and gate voltage, which is consistent with a short and diffusive junction model.

Improved Mechanical Stability of Acetoxypropyl Cellulose upon Blending with Ultranarrow PbS Nanowires in Langmuir Monolayer Matrix

Cellulose and cellulose derivatives have long been used as membrane fabrication. Langmuir monolayer behavior, which naturally mimics membranes, of acetoxypropyl cellulose (APC) and lead sulfide (PbS) nanowire mixtures at different volume ratios is reported. Surface pressure (π)-area (A) isotherms of APC and PbS nanowires mixtures at different volume ratios show a gradual decrease in the monolayer area with increasing volume fraction of PbS nanowires. Change of surface potential with monolayer area at different volume ratios also reveals a gradual increase in the surface potential indicating incorporation of PbS nanowires within APC matrix. The compressibility and elastic constants measurements reveal an enhancement of the elasticity upon incorporation of PbS nanowires up to certain volume fractions. An enhancement in stability of the blend is observed upon PbS nanowire incorporation to the APC matrix. Rheological measurements also support the robustness of the mixture of APC and PbS nanowires in 3D bulk phase. Such robust ultrathin films of cellulose based-nanowire blend obtained by means of the Langmuir technique may lead to novel routes for designing cellulosic-based thin films and membranes.

The Optoelectronic Properties of PbS Nanowire Field-Effect Transistors

We report on the optoelectronic properties of individual PbS nanowires prepared by gas-phase substitution reaction of pregrown CdS nanowires. The PbS nanowires synthesized by this method were found to be single crystals with high quality. A combination of electron-beam lithography and a lift-off process was utilized to fabricate individual 62-nm-thick PbS nanowire field-effect transistors (FETs). The nanowire FETs showed pronounced photoconductivity under light illumination while they were highly resistive in the dark environment. The conductivity increased by more than 40 folds in the presence of light. Our results are the first demonstration of the highly efficient photoresponse of individual single-crystalline PbS nanowires and provide insights into future works on nanostructured PbS optoelectronics.

Synthesizing Axial Inserting p–n Heterojunction Nanowire Arrays for Realizing Synergistic Performance

Consideration of the material design and components match on structure and energy, the solid-solid combined nanowires of p-type conductive polymer of poly[3-thiophene carboxylic acid methyl ester] (PTCM) and n-type inorganic semiconductor PbS was prepared with a 2.57 μm(2) heterojunction interface. The axial deeply inserting heterojunction nanowire arrays exhibited excellent rectifying features and diode nature, as well as obvious electrical switching behavior, which are much excelled individual components of PTCM and PbS nanowire arrays for realizing synergistic performance.

Direct synthesis of high-density lead sulfide nanowires on metal thin films towards efficient infrared light conversion

We report chemical-vapor-deposition (CVD) synthesis of high-density lead sulfide (PbS) nanowire arrays and nano pine trees directly on Ti thin films, and the fabrication of photovoltaic devices based upon the PbS nanowires. The as-grown nanowire arrays are largely vertically aligned to the substrates and are uniformly distributed over a relatively large area. Field effect transistors incorporating single PbS nanowires show p-type conduction and high mobilities. These catalytic metal thin films also serve as photocarrier collection electrodes and greatly facilitate device integration. For the first time, we have fabricated Schottky junction photovoltaic devices incorporating PbS nanowires, which demonstrate the capability of converting near-infrared light to electricity. The PbS nanowire devices are stable in air and their external quantum efficiency shows no significant decrease over a period of 3 months in air. We have also compared the photocurrent direction and quantum efficiencies of photovoltaic devices made with different metal electrodes, and the results are explained by band bending at the Schottky junction. Our research shows that PbS nanowires are promising building blocks for collecting near-infrared solar energy.

Electric Field Dependent Photocurrent Decay Length in Single Lead Sulfide Nanowire Field Effect Transistors

We determined the minority carrier diffusion length to be ∼1 μm in single PbS nanowire field effect transistors by scanning photocurrent microscopy. PbS nanowires grown by the vapor-liquid-solid method were p-type with hole mobilities up to 49 cm(2)/(V s). We measured a photoresponse time faster than 14 μs with near-unity charge separation efficiency at the contacts. For the first time, we also observed a field-dependent photocurrent decay length, indicating a drift dominant carrier transport at high bias.

Formation of PbS Nanowire Pine Trees Driven by Screw Dislocations

The basic characteristics of nanowire growth driven by screw dislocations were investigated by synthesizing hierarchical lead sulfide (PbS) nanowire "pine trees" using chemical vapor deposition of PbCl(2) and S precursors and systematically observing the effects of various growth parameters, such as hydrogen flow, temperature, pressure, and the growth substrates employed. Statistical surveys showed that the growth rate of the dislocation-driven trunk is about 6 mum/min and that of the vapor-liquid-solid (VLS) driven branch nanowire is about 1.2 mum/min under the typical reaction conditions at 600 degrees C, 900 Torr, and a hydrogen flow rate of 1.5 sccm. The onset of hydrogen flow plus the presence of fresh silicon have been identified as the critical ingredients for generating PbS nanowire trees reproducibly. To explain the experimental findings in the context of classical crystal growth theory, the former is suggested to create a spike in supersaturation of the actual sulfur precursor H(2)S and initiate dislocations with screw components that then propagate anisotropically to form the PbS nanowire trunks. Maintaining suitable hydrogen flow provides a favorable low supersaturation that promotes dislocation-driven trunk nanowire growth and enables the simultaneous VLS nanowire growth of branches. Furthermore, thermodynamic consideration and experiments showed that silicon fortuitously controls the supersaturation by reversibly reacting with H(2)S to form SiS(2) and that SiS(2) can also be a viable precursor for PbS nanowire growth. The key requirements of screw dislocation-driven nanowire growth are summarized. This study provides some general guidelines for further nanowire growth driven by screw dislocations.

Quantum confinement and phase transition in PbS nanowire: A first principles study

We report first principles density functional calculations of the electronic structures and energy bandgaps ( Δ E g ) in PbS nanowires (NW). The Δ E g is tuned by varying the diameter of the NW – revealing the role of quantum confinement. Compressive radial strain (CS) on the NW is shown to be responsible for a semiconducting to metallic phase transition. When compared with the valence band, the conduction band (CB) of the NW, which has a significant contribution from the excited 3 d-orbital of S, is found to be more sensitive to the CS with the CB minimum shifting towards and eventually crossing the Fermi energy as CS increases. The origin of the observed phase transition in a recent experiment is attributed to the CS on the PbS nanowire.

Environmentally benign and cost-effective synthesis of well-aligned nanoporous PbS nanowire architectures

Download options Please wait... Supplementary files Fig. S1–4 PDF (6465K) Article information DOI https://doi.org/10.1039/B808559E Article type Paper Submitted 21 May 2008 Accepted 16 Jul 2008 First published 20 Aug 2008 Download Citation J. Mater. Chem., 2008,18, 4631-4635 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Environmentally benign and cost-effective synthesis of well-aligned nanoporous PbS nanowire architectures X. Shen and X. Yan, J. Mater. Chem., 2008, 18, 4631 DOI: 10.1039/B808559E To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Xiao-Fang Shen Xiu-Ping Yan

Correlation between structural and optical properties of 30 nm and 60 nm lead sulfide nanowires

PbS nanowires with 30 nm and 60 nm diameter fabricated under the same condition of electrochemical deposition with sulfuric and oxalic anodic alumina membranes (AAM), respectively, have been successfully prepared in order to study their optical properties in relation to their size. Scanning electron microscopy indicates that the 60 nm PbS nanowire arrays have the same shape with the 30 nm. X-ray diffraction result shows that 60 nm PbS nanowires are crystalline and have a highly (200) preferential orientation like 30 nm ones. UV spectrum considers the nanowire size decrease as the absorption peak shifts to the blue. The quantum confinement effects compared between 30 nm and 60 nm PbS nanowire arrays were observed by the measurements of ultraviolet–visible absorption spectroscopy (UV–vis).

Synthesis and optical properties of ordered 30 nm PbS nanowire arrays fabricated into sulfuric anodic alumina membrane

Crystalline PbS nanowire arrays have been successfully fabricated by AC applied DC electrochemical deposition from aqueous solutions of dimethylsulfoxide DMSO solution containing lead chloride and elemental sulfur into sulfuric anodic alumina membranes (AAM). These nanowires have uniform diameters of approximately 30 nm, and their lengths are up to tens of micrometers. Scanning electron microscopy indicates that the ordered PbS nanowire arrays are completely embedded. The results of X-ray diffraction show that the as-synthesized nanowires are crystalline with highly preferential orientation. Energy dispersive spectrometer analysis shows that the composition ratio is very close to 1:1. Finally PL and UV–VIS illustrate the quantum confinement effects of PbS nanowire arrays.

Orthogonal PbS Nanowire Arrays and Networks and Their Raman Scattering Behavior

Three-dimensional, orthogonal lead sulfide (PbS) nanowire arrays and networks have been prepared by using a simple, atmospheric pressure chemical vapor deposition (APCVD) method. These uniform nanowires (average diameter 30 nm) grow epitaxially from the surface of the initial PbS crystal seeds and form orthogonal arrays and networks in space. The growth mechanism has been explored, and the process was classified as homogeneous, epitaxial growth in the 200 directions. Furthermore, Raman spectra of PbS nanowires are reported here, and their characteristic Raman peak (190 cm(-1), no shoulder) could be used as a unique probe for the study of PbS nanomaterials.