三方晶硒纳米线的大面积合成及其场效应晶体管特性

采用液相反应成功制备了高质量硒纳米线。利用透射电镜（TEM）、高分辨透射电镜（HRTEM）以及X射线衍射仪（XRD）研究了纳米的形貌结构特征。结果表明,硒纳米线为单晶结构,生长方向沿[001]面,平行于螺旋轴。结合光刻技术及磁控溅射镀膜技术,成功制备了硒纳米线场效应晶体管器件。初步测试表明,这种硒纳米线为p型半导体。     

Blueshift of electroluminescence from single n-InP nanowire/p-Si heterojunctions due to the Burstein-Moss effect

Single-crystalline n-type InP nanowires (NWs) with different electron concentrations were synthesized on Si substrates via the vapor phase transport method. The electrical properties of the InP nanowires were investigated by fabricating and measuring single NW field-effect transistors (FETs). Single InP NW/p(+)-Si heterojunctions were fabricated, and electroluminescence (EL) spectra from them were studied. It was found that both the photoluminescence (PL) spectra of the InP NWs and the EL spectra of the heterojunctions blueshift from 920 to 775?nm when the electron concentrations of the InP NWs increase from 2 × 10(17) to 1.4 × 10(19)?cm(-3). The blueshifts can be attributed to the Burstein-Moss effect rather than the quantum confinement effect in the InP NWs. The large blueshifts observed in this study indicate a potential application of InP NWs in nano-multicolour displays.     

InAs Nanowire Devices with Strong Gate Tunability:Fundamental Electron Transport Properties and Application Prospects:A Review

The high electron mobility has granted indium arsenide(InAs) nanowires(NWs) as an important class of nanomaterials for high performance electronics such as field-effect transistors(FETs).We reviewed recent progresses on the studies of quantum coherence,gate tunable one-dimensional(1D) confinement and spin orbit interaction(SOI) in InAs NW based electronic and thermoelectric transport devices.We also demonstrated gas sensing response of InAs NW FETs and elucidated the mechanism via a gating experiment.By using InAs NWs as an example,these fundamental transport studies have shed important lights on the potential thermoelectric,spintronic and gas sensing applications of semiconductor NWs where the 1D confinement,SOI or surface states effects are exploited.     

Non‐Volatile Ferroelectric Memory with Position‐Addressable Polymer Semiconducting Nanowire

One‐dimensional nanowires (NWs) have been extensively examined for numerous potential nano‐electronic device applications such as transistors, sensors, memories, and photodetectors. The ferroelectric‐gate field effect transistors (Fe‐FETs) with semiconducting NWs in particular in combination with ferroelectric polymers as gate insulating layers have attracted great attention because of their potential in high density memory integration. However, most of the devices still suffer from low yield of devices mainly due to the ill‐control of the location of NWs on a substrate. NWs randomly deposited on a substrate from solution‐dispersed droplet made it extremely difficult to fabricate arrays of NW Fe‐FETs. Moreover, rigid inorganic NWs were rarely applicable for flexible non‐volatile memories. Here, we present the NW Fe‐FETs with position‐addressable polymer semiconducting NWs. Polymer NWs precisely controlled in both location and number between source and drain electrode were achieved by direct electrohydrodynamic NW printing. The polymer NW Fe‐FETs with a ferroelectric poly(vinylidene fluoride‐co‐trifluoroethylene) exhibited non‐volatile ON/OFF current margin at zero gate voltage of approximately 10² with time‐dependent data retention and read/write endurance of more than 10⁴ seconds and 10² cycles, respectively. Furthermore, our device showed characteristic bistable current hysteresis curves when being deformed with various bending radii and multiple bending cycles over 1000 times.     

High mobility field effect transistor from solution-processed needle-like tellurium nanowires

Well-dispersed and uniform needle-like tellurium nanowires (NWs) have been fabricated in high yield by an environmentally-friendly hydrothermal method. It is found that beta-cyclodextrin ligands and reaction temperature play a great role on the morphology of Te NWs. Uniform needle-like Te NWs can only be obtained at suitable concentration of beta-CD and reaction temperature. A possible mechanism for the formation of the needle-liked Te NWs is discussed based on the experiment results briefly. High quality single Te NW field effect transistors are prepared through photolithographic patterning. By optimizing electrode and surface treatments, the NW FET has a high carrier mobility of 299 cm2V(-1)s(-1), which is the highest value ever reported for Te NW-based FETs. The performance is influenced by purity, crystallinity, surface species of NWs and metal contacts of NW device.     

Role of confinement on carrier transport in Ge-Si(x)Ge(1-x) core-shell nanowires

We examine the impact of shell content and the associated hole confinement on carrier transport in Ge-Si(x)Ge(1-x) core-shell nanowires (NWs). Using NWs with different Si(x)Ge(1-x) shell compositions (x = 0.5 and 0.7), we fabricate NW field-effect transistors (FETs) with highly doped source/drain and examine their characteristics dependence on shell content. The results demonstrate a 2-fold higher mobility at room temperature, and a 3-fold higher mobility at 77K in the NW FETs with higher (x = 0.7) Si shell content by comparison to those with lower (x = 0.5) Si shell content. Moreover, the carrier mobility shows a stronger temperature dependence in Ge-Si(x)Ge(1-x) core-shell NWs with high Si content, indicating a reduced charge impurity scattering. The results establish that carrier confinement plays a key role in realizing high mobility core-shell NW FETs.     

Layer-by-layer assembly of nanowires for three-dimensional, multifunctional electronics

We report a general approach for three-dimensional (3D) multifunctional electronics based on the layer-by-layer assembly of nanowire (NW) building blocks. Using germanium/silicon (Ge/Si) core/shell NWs as a representative example, ten vertically stacked layers of multi-NW field-effect transistors (FETs) were fabricated. Transport measurements demonstrate that the Ge/Si NW FETs have reproducible high-performance device characteristics within a given device layer, that the FET characteristics are not affected by sequential stacking, and importantly, that uniform performance is achieved in sequential layers 1 through 10 of the 3D structure. Five-layer single-NW FET structures were also prepared by printing Ge/Si NWs from lower density growth substrates, and transport measurements showed similar high-performance characteristics for the FETs in layers 1 and 5. In addition, 3D multifunctional circuitry was demonstrated on plastic substrates with sequential layers of inverter logical gates and floating gate memory elements. Notably, electrical characterization studies show stable writing and erasing of the NW floating gate memory elements and demonstrate signal inversion with larger than unity gain for frequencies up to at least 50 MHz. The ability to assemble reproducibly sequential layers of distinct types of NW-based devices coupled with the breadth of NW building blocks should enable the assembly of increasing complex multilayer and multifunctional 3D electronics in the future.     

Large anisotropy of electrical properties in layer-structured In2Se3 nanowires

Layer-structured indium selenide (In 2Se 3) nanowires (NWs) have large anisotropy in both shape and bonding. In 2Se 3 NWs show two types of growth directions: [11-20] along the layers and [0001] perpendicular to the layers. We have developed a powerful technique combining high-resolution transmission electron microscopy (HRTEM) investigation with single NW electrical transport measurement, which allows us to correlate directly the electrical properties and structure of the same individual NWs. The NW devices were made directly on a 50 nm thick SiN x membrane TEM window for electrical measurements and HRTEM study. NWs with the [11-20] growth direction exhibit metallic behavior while the NWs grown along the [0001] direction show n-type semiconductive behavior. Excitingly, the conductivity anisotropy reaches 10 (3)-10 (6) at room temperature, which is 1-3 orders magnitude higher than the bulk ratio.     

Sn-catalyzed synthesis of SnO2 nanowires and their optoelectronic characteristics

We report the rational synthesis of one-dimensional SnO(2) nanowires (SnO(2)NWs) via a Sn-catalyzed vapor-liquid-solid (VLS) growth mechanism, in which Sn nanoparticles can direct the oriented growth of SnO(2)NWs at high temperature. I-V measurement of a field effect transistor made of individual SnO(2)NWs exhibits typical n-type semiconducting characteristics with an electron mobility and concentration of 14.36?cm(2)?V( - 1)?s( - 1) and 1.145 × 10(17)?cm( - 3), respectively. The SnO(2)NW-based photodetector shows a high sensitivity to UV light radiation, and a fast light response speed of millisecond rise time/fall time with excellent stability and reproducibility, whereas it is nearly blind to illumination with wavelengths in the visible range. Detailed reasons to account for the detection selectivity and rapid response speed are proposed. The generality of the above results suggests that our SnO(2)NW photodetectors have potential application in nanoscaled optoelectronic devices.     

Direct gravure printing of silicon nanowires using entropic attraction forces

The development of a method for large-scale printing of nanowire (NW) arrays onto a desired substrate is crucial for fabricating high-performance NW-based electronics. Here, the alignment of highly ordered and dense silicon (Si) NW arrays at anisotropically etched micro-engraved structures is demonstrated using a simple evaporation process. During evaporation, entropic attraction combined with the internal flow of the NW solution induced the alignment of NWs at the corners of pre-defined structures, and the assembly characteristics of the NWs were highly dependent on the polarity of the NW solutions. After complete evaporation, the aligned NW arrays are subsequently transferred onto a flexible substrate with 95% selectivity using a direct gravure printing technique. As a proof-of-concept, flexible back-gated NW field-effect transistors (FETs) are fabricated. The fabricated FETs have an effective hole mobility of 17.1 cm(2) ·V(-1) ·s(-1) and an on/off ratio of ~2.6 × 10(5) .     

A ZnO nanowire vacuum pressure sensor

In this study, we report the growth and characterization of lateral ZnO nanowires (NWs) on ZnO:Ga/glass templates. Using x-ray diffraction and micro-Raman spectroscopy, it was found that crystal quality of the as-grown ZnO NWs is good. It was also found that the average length and average diameter of the laterally grown ZnO NWs were 5?μm and 30?nm, respectively. A vacuum pressure sensor was then fabricated using a single NW bridging across two electrodes. By measuring the current-voltage characteristics of the samples at low pressure, we found that the currents were of 17, 34.28, 57.37 and 96.06?nA for the ZnO NW measured at 1 × 10(-3)?Torr, 1 × 10(-4)?Torr, 3 × 10(-5)?Torr and 5 × 10(-6)?Torr, respectively. These values suggest that the laterally grown ZnO NWs prepared in this study are potentially useful for vacuum pressure sensing.     

Development of ultra-high density silicon nanowire arrays for electronics applications

This article reviews our recent progress on ultra-high density nanowires (NWs) array-based electronics. The superlattice nanowire pattern transfer (SNAP) method is utilized to produce aligned, ultra-high density Si NW arrays. We fi rst cover processing and materials issues related to achieving bulk-like conductivity characteristics from 10 20 nm wide Si NWs. We then discuss Si NW-based fi eld-effect transistors (FETs). These NWs & NW FETs provide terrifi c building blocks for various electronic circuits with applications to memory, energy conversion, fundamental physics, logic, and others. We focus our discussion on complementary symmetry NW logic circuitry, since that provides the most demanding metrics for guiding nanofabrication. Issues such as controlling the density and spatial distribution of both p-and n-type dopants within NW arrays are discussed, as are general methods for achieving Ohmic contacts to both p-and n-type NWs. These various materials and nanofabrication advances are brought together to demonstrate energy effi cient, complementary symmetry NW logic circuits.     

Photocurrent polarization anisotropy of randomly oriented nanowire networks

While the polarization sensitivity of single or aligned NW ensembles is well-known, this article reports on the existence of residual photocurrent polarization sensitivities in random NW networks. In these studies, CdSe and CdTe NWs were deposited onto glass substrates and contacted with Au electrodes separated by 30-110 microm gaps. SEM and AFM images of resulting devices show isotropically distributed NWs between the electrodes. Complementary high resolution TEM micrographs reveal component NWs to be highly crystalline with diameters between 10 and 20 nm and with lengths ranging from 1 to 10 microm. When illuminated with visible (linearly polarized) light, such random NW networks exhibit significant photocurrent anisotropies rho = 0.25 (sigma = 0.04) [rho = 0.22 (sigma = 0.04)] for CdSe (CdTe) NWs. Corresponding bandwidth measurements yield device polarization sensitivities up to 100 Hz. Additional studies have investigated the effects of varying the electrode potential, gap width, and spatial excitation profile. These experiments suggest electrode orientation as the determining factor behind the polarization sensitivity of NW devices. A simple geometric model has been developed to qualitatively explain the phenomenon. The main conclusion from these studies, however, is that polarization sensitive devices can be made from random NW networks without the need to align component wires.     

Rational synthesis of p-type zinc oxide nanowire arrays using simple chemical vapor deposition

We report, for the first time, the synthesis of the high-quality p-type ZnO NWs using a simple chemical vapor deposition method, where phosphorus pentoxide has been used as the dopant source. Single-crystal phosphorus doped ZnO NWs have their growth axis along the 001 direction and form perfect vertical arrays on a-sapphire. P-type doping was confirmed by photoluminescence measurements at various temperatures and by studying the electrical transport in single NWs field-effect transistors. Comparisons of the low-temperature PL of unintentionally doped ZnO (n-type), as-grown phosphorus-doped ZnO, and annealed phosphorus-doped ZnO NWs show clear differences related to the presence of intragap donor and acceptor states. The electrical transport measurements of phosphorus-doped NW FETs indicate a transition from n-type to p-type conduction upon annealing at high temperature, in good agreement with the PL results. The synthesis of p-type ZnO NWs enables novel complementary ZnO NW devices and opens up enormous opportunities for nanoscale electronics, optoelectronics, and medicines.     

An aqueous solution-based doping strategy for large-scale synthesis of Sb-doped ZnO nanowires

An aqueous solution-based doping strategy was developed for controlled doping impurity atoms into a ZnO nanowire (NW) lattice. Through this approach, antimony-doped ZnO NWs were successfully synthesized in an aqueous solution containing zinc nitrate and hexamethylenetetramine with antimony acetate as the dopant source. By introducing glycolate ions into the solution, a soluble antimony precursor (antimony glycolate) was formed and a good NW morphology with a controlled antimony doping concentration was successfully achieved. A doping concentration study suggested an antimony glycolate absorption doping mechanism. By fabricating and characterizing NW-based field effect transistors (FETs), stable p-type conductivity was observed. A field effect mobility of 1.2 cm(2) V(-1) s(-1) and a carrier concentration of 6 × 10(17) cm(-3) were achieved. Electrostatic force microscopy (EFM) characterization on doped and undoped ZnO NWs further illustrated the shift of the metal-semiconductor barrier due to Sb doping. This work provided an effective large-scale synthesis strategy for doping ZnO NWs in aqueous solution.     

Deformable Organic Nanowire Field‐Effect Transistors

Deformable electronic devices that are impervious to mechanical influence when mounted on surfaces of dynamically changing soft matters have great potential for next‐generation implantable bioelectronic devices. Here, deformable field‐effect transistors (FETs) composed of single organic nanowires (NWs) as the semiconductor are presented. The NWs are composed of fused thiophene diketopyrrolopyrrole based polymer semiconductor and high‐molecular‐weight polyethylene oxide as both the molecular binder and deformability enhancer. The obtained transistors show high field‐effect mobility >8 cm² V^?1 s^?1 with poly(vinylidenefluoride‐ co ‐trifluoroethylene) polymer dielectric and can easily be deformed by applied strains (both 100% tensile and compressive strains). The electrical reliability and mechanical durability of the NWs can be significantly enhanced by forming serpentine‐like structures of the NWs. Remarkably, the fully deformable NW FETs withstand 3D volume changes (>1700% and reverting back to original state) of a rubber balloon with constant current output, on the surface of which it is attached. The deformable transistors can robustly operate without noticeable degradation on a mechanically dynamic soft matter surface, e.g., a pulsating balloon (pulse rate: 40 min^?1 (0.67 Hz) and 40% volume expansion) that mimics a beating heart, which underscores its potential for future biomedical applications.     

Growth direction modulation and diameter-dependent mobility in InN nanowires

Diameter-dependent electrical properties of InN nanowires (NWs) grown by chemical vapor deposition have been investigated. The NWs exhibited interesting properties of coplanar deflection at specific angles, either spontaneously, or when induced by other NWs or lithographically patterned barriers. InN NW-based back-gated field effect transistors (FETs) showed excellent gate control and drain current saturation behaviors. Both NW conductance and carrier mobility calculated from the FET characteristics were found to increase regularly with a decrease in NW diameter. The observed mobility and conductivity variations have been modeled by considering NW surface and core conduction paths.     

Growth of SiO(x) nanowires by laser ablation

Amorphous SiO(x) nanowires (NWs) were synthesized using laser ablation of silicon-containing targets. The influence of various parameters such as target composition, substrate type, substrate temperature and carrier gas on the growth process was studied. The NWs were characterized using high resolution scanning and transmission electron microscopes (HRSEM and HRTEM) with their attachments: electron dispersive spectroscopy (EDS) and energy electron loss spectroscopy (EELS). A metal catalyst was found essential for the NW growth. A growth temperature higher than 1000?°C was necessary for the NW formation using an Ar-based carrier gas at 500?Torr. The use of Ar-5%H(2) instead of pure Ar resulted in a higher yield and longer NWs. Application of a diffusion barrier on top of the Si substrate guaranteed the availability of metal catalyst droplets on the surface, essential for the NW growth. Ni was found to be a better catalyst than Au in terms of the NW yield and length. Two alternative sequences for the evolution of the amorphous SiO(x) NWs were considered: (a)?the formation of Si NWs first and their complete oxidation afterwards, which seems to be doubtful, (b)?the direct formation of SiO(x) NWs, which is more likely to occur. The direct formation mechanism was proposed to advance in three stages: preferential adsorption of SiO(x) clusters on the catalyst surface first, a successive surface diffusion to the catalyst droplet lower hemisphere, and finally the formation and growth of the NW between the catalyst and the substrate.     

Growth of high-density titanium silicide nanowires in a single direction on a silicon surface

Understanding the growth mechanisms of nanowires is essential for their successful implementation in advanced devices applications. In situ ultrahigh-vacuum transmission electron microscopy has been applied to elucidate the interaction mechanisms of titanium disilicide nanowires (TiSi2 NWs) on Si(111) substrate. Two phenomena were observed: merging of the two NWs in the same direction, and collapse of one NW on a competing NW in a different direction when they meet at the ends. On the other hand, as one NW encounters the midsection of the other NW in a different direction, it recedes in favor of bulging of the other NW at the midsection. Since crystallographically the nanowires are favored to grow on Si(110) only in the [1 -1 0] direction, this crucial information has been fruitfully exploited to focus on the growth of a high density of long and high-aspect-ratio Ti silicide NWs parallel to the surface on Si(110) in a single direction. The achievement in growth of high-density NWs in a single direction represents a significant advance in realizing the vast potential for applications of silicide NWs in nanoelectronics devices.     

Optical properties of conductive silver-nanowire films with different nanowire lengths

Transparent electrodes made of silver nanowires (Ag NWs) exhibit a higher flexibility than conventional indium tin oxide electrodes.For this reason,Ag NWs may find applications in future flexible electronic and optoelectronic devices.However,different optoelectronic devices have different specific requirements for Ag NWs.For example,the optical transmittance haze is an important but rarely studied aspect of Ag NW films.In this study,the optical transmittance and optical scattering of long (5-50 μm,L-NWs) and short (1-20 μm,S-NWs) Ag NW films were investigated.The L-NWs exhibited better optical transmission than the S-NWs,whereas the S-NWs exhibited better light-scattering properties than the L-NWs.Our results indicate that the L-NWs are suitable for touch-screen displays,whereas the S-NWs are better suited as transparent conductive films for solar cells.We analyzed the scattering ratio of forward-scattered light to backscattered light for both the L-NWs and S-NWs and discovered that the mesh size affected the scattering ratio.For longer wavelengths,a larger mesh yielded a higher backscattering ratio,whereas a smaller mesh yielded a lower backscattering ratio.We formulated an equation for calculating the reflection haze using the total reflection (Ag NWs/glass),R and the reflection of glass,R0.The reflection haze of the S-NWs and L-NWs exhibited different trends in the visible-near-infrared region.An omnidirectional scattering model for the Ag NWs was used to evaluate the Ag NW scattering properties.The results of this study have great significance for the evaluation of the performance of Ag NWs in optoelectronic devices.