Effect of annealing temperature on electrical properties of Au/polyvinyl alcohol/n-InP Schottky barrier structure

In the present work, thin film of polyvinyl alcohol (PVA) is fabricated on n-type InP substrate as an interfacial layer for electronic modification of Au/n-InP Schottky contact. The electrical characteristics of Au/PVA/n-InP Schottky diode are determined at annealing temperature in the range of 100-300 °C by current-voltage (I-V) and capacitance-voltage (C-V) methods. The Schottky barrier height and ideality factor (n) values of the as-deposited Au/PVA/n-InP diode are obtained at room temperature as 0.66 eV (I-V), 0.82 eV (C-V) and 1.32, respectively. Upon annealing at 200 °C in nitrogen atmosphere for 1 min, the barrier height value increases to 0.81 eV (I-V), 0.99 eV (C-V) and ideality factor decreases to 1.18. When the contact is annealed at 300 °C, the barrier height value decreases to 0.77 eV (I-V), 0.96 eV (C-V) and ideality factor increases to 1.22. It is observed that the interfacial layer of PVA increases the barrier height by the influence of the space charge region of the Au/n-InP Schottky junction. The discrepancy between Schottky barrier heights calculated from I-V and C-V measurements is also explained. Further, Cheung's functions are used to extract the series resistance of Au/PVA/n-InP Schottky diode. The interface state density as determined by Terman's method is found to be 1.04 × 10¹² and 0.59 × 10¹² cm^− 2 eV^− 1 for the as-deposited and 200 °C annealed Au/PVA/n-InP Schottky diodes. Finally, it is seen that the Schottky diode parameters changed with increase in the annealing temperature.     

Preparation of Au nanoparticle-decorated ZnO/NiO heterostructure via nonsolvent method for high-performance photocatalysis

In this paper, we present a novel physical (or nonsolvent) route to fabricate a kind of Au/ZnO/NiO heterostructure photocatalytic composite. That is, a Zn layer upon Ni foam substrate is prepared by pulse electrodeposition, then the ZnO nanoneedle/NiO heterostructural composite is obtained via thermal oxidation, and at last, the composite is modified with the dispersively deposited Au nanoparticles (Au NPs) by ion sputtering. The surface plasmon resonance effect of the Au NPs significantly enhances the light absorption. Meanwhile, the Au NPs form a Schottky barrier with ZnO nanoneedles and further inhibit the recombination of photogenerated electron–hole pairs. In addition, due to the nonsolvent conditions, the introduction of impurities is avoided, and thus it shows strong photocatalytic stability. The experimental results reveal that, the optimized Au/ZnO/NiO composite exhibits up to two times photocatalytic performance on RB degradation and higher stability than that of regular ZnO/NiO composite. The present experimental strategy can also be used for other noble metals, and it is expected to have important application prospects in the fields of environmental purification, solar cells, hydrogen generation, etc.     

Electronic parameters of high barrier Au/Rhodamine-101/n-Inp Schottky diode with organic ?nterlayer

In this work, we present that Rhodamine-101 (Rh-101) organic molecules can control the electrical characteristics of conventional Au/n-InP metal-semiconductor contacts. An Au/n-InP Schottky junction with Rh-101 interlayer has been formed by using a simple cast process. A potential barrier height as high as 0.88 eV has been achieved for Au/Rh-101/n-InP Schottky diodes, which have good current-voltage (I-V) characteristics. This good performance is attributed to the effect of formation of interfacial organic thin layer between Au and n-InP. By using capacitance-voltage measurement of the Au/Rh-101/n-InP Schottky diode the diffusion potential and the barrier height have been calculated as 0.78 V and 0.88 eV, respectively. From the I-V measurement of the diode under illumination, short circuit current and open circuit voltage have been extracted as 1.70 μA and 240 mV, respectively.     

Fabrication of Ni nanostructures on p-Si by scanning probe lithography on Si3N4 films and selective electrodeposition

Ni-Si nano Schottky junctions are fabricated by the combined process of scanning probe lithography and electrodeposition. The Si3N4 film was patterned by probe-induced oxidation and became a mask for selective electrodeposition of Ni on p-Si substrate. The Ni pattern consists of Ni nano dots, whose diameter is less then 60 nm. The composition and ferromagnetism of Ni dots are verified by energy dispersive spectrum and magnetic force microscopy. The schottky barrier of Ni-Si nano contact is 0.52 V determined by the I-V measurement of conducting atomic force microscopy (CAFM). From current mapping images, it shows that chemical impurity at the Ni-Si interfaces can result in the poor conductance of the junctions.     

Electrical characteristics and stability of gold and palladium Schottky contacts on ZnO nanorods

The electrical characteristics and stability of Pd and Au Schottky contacts on ZnO nanorods grown on glass substrate have been investigated. The nanorods were grown using the aqueous chemical growth method. The nanorods were characterized with scanning electron microscopy (SEM), x-ray diffraction (XRD) and photoluminescence (PL). Prior to the metal contact deposition, an insulating PMMA layer was deposited between the nanorods. The best-produced Schottky contact was an as-deposited Pd/ZnO contact with an ideality factor of 1.74 ± 0.43 and a barrier height of 0.67 ± 0.09?eV. The relatively high ideality factor indicates that the current transport cannot be described by pure thermionic transport. The presence of surface states due to the high evaporation pressure is probably the reason for the high ideality factor. Post metal deposition annealing at 150?°C for 30?min in air lowered the barrier height and decreased the Au/ZnO ideality factor but increased it for Pd/ZnO. The current follows ohmic behavior when the applied forward bias, V(forward), is lower than 0.1?V, whereas for V(forward) between 0.1 and 0.45?V the current follows I～exp(cV), and at higher forward biases the current-voltage characteristics follow the relation I～V(2), indicating that the space-charge current-limiting mechanism is dominating the current transport.     

Schottky barrier characteristics and internal gain mechanism of TiO2 UV detectors

High-responsivity metal-semiconductor-metal TiO(2) UV photodetectors with Ni and Au electrodes were fabricated identically. Their Schottky barrier heights and photocurrent gain mechanism were studied. The effective barrier height Φ and ideality factor n were evaluated according to the thermionic emission theory. The result that Φ(Ni) was lower than Φ(Au) may be attributed to the electron transfer from Ni to the TiO(2) substrate, which would lead to a dipole layer and, accordingly, decrease the barrier height. In addition, the I-V characteristics of the Ni/TiO(2)/Ni and Au/TiO(2)/Au photodetectors were observed. A significant internal gain was obtained, and the mechanism of the internal gain was studied by the phototransistor model in detail.     

Enhanced Piezo‐Photoelectric Catalysis with Oriented Carrier Migration in Asymmetric Au−ZnO Nanorod Array

Current photocatalytic semiconductors often have low catalytic performance due to limited light utilization and fast charge carrier recombination. Formation of Schottky junction between semiconductors and plasmonic metals can broaden the light absorption and facilitate the photon‐generated carriers separation. To further amplify the catalytic performance, herein, an asymmetric gold‐zinc oxide (Asy‐Au?ZnO) nanorod array is rationally designed, which realizes the synergy of piezocatalysis and photocatalysis, as well as spatially oriented electron?hole pairs separation, generating a significantly enhanced catalytic performance. In addition to conventional properties from noble metal/semiconductor Schottky junction, the rationally designed heterostructure has several additional advantages: 1) The piezoelectric ZnO under light and mechanical stress can directly generate charge carriers; 2) the Schottky barrier can be reduced by ZnO piezopotential to enhance the injection efficiency of hot electrons from Au nanoparticles to ZnO; 3) the unique asymmetric nanorod array structure can achieve a spatially directed separation and migration of the photon‐generated carriers. When ultrasound and all‐spectrum light irradiation are exerted simultaneously, the Asy‐Au?ZnO reaches the highest catalytic efficiency of 95% in 75 min for dye degradation. It paves a new pathway for designing unique asymmetric nanostructures with the synergy of photocatalysis and piezocatalysis.     

Imaging buried organic islands by spatially resolved ballistic electron emission spectroscopy

The well-known Au/n-Si(111) Schottky interface is modified by a discontinuous pentacene film (～1.5?nm thick) and studied using spatially resolved ballistic electron emission spectroscopy (BEES). The pentacene film introduced subtle changes to the interface which cannot be definitively detected by current-voltage measurements or a standard BEES analysis of the barrier height. In contrast, analyzing the BEES results in a dual-parameter (transmission attenuation and barrier height) space allows the effect of the pentacene film on the Au/n-Si(111) interface to be clearly demonstrated. We found that the pentacene film behaves like a tunneling barrier and increases the distribution of local barrier heights with a tendency toward lower values. Our results highlight the potential of the dual-parameter BEES analysis for understanding local interface modification by molecules.     

金属/Hg1-xMnxTe接触的I-V特性研究

分别采用溅射和蒸发镀膜法在Hg1-xMnxTe试样表面形成了Au/Hg1-xMnxTe和Al/Hg1-xMnxTe接触,并用Aligent4155c I-V测试仪对其I-V特性进行了测量,随后对试样在10%NH4F:10%H2O2:H2O中进行了钝化处理,并对处理后的试样再次进行了I-V测量,对于测试结果用热电子发射-扩散理论进行了分析.结果表明:Au与Hg1-xMnxTe形成了良好的欧姆接触,而Al与Hg1-xMnxTe形成了具有整流特性的肖特基接触,其肖特基势垒的理论推算值为0.38eV.钝化处理后的试样,其表面漏电现象明显降低,Au/Hg1-xMnxTe接触的电流下降幅度在0.1V时最大,为76.1%;而Al/Hg1-xMnxTe接触在0.2V时最大,为93.2%.随着偏压的进一步增大,两种接触的电流减小的幅度都逐渐变小.     

Electrical properties of a novel 1,3-bis-(p-iminobenzoic acid) indane Langmuir-Blodgett films containing ZnS nanoparticles

ZnS nanoparticles have been formed in a newly synthesized 1,3-bis-(p-iminobenzoic acid) indane (IBI) by exposing Zn2+ doped multilayered Langmuir-Blodgett (LB) film to H2S gas after the growth. The formation of ZnS nanoparticles in the LB film structure was verified by measuring UV-Visible absorption spectra. DC electrical measurements were carried out for thin films of IBI prepared in a metal/LB films/metal sandwich structure with and without ZnS nanoparticles. It was observed that ZnS nanoparticles in the LB films cause a blue-shift in the absorption spectra as well as a decrease in both capacitance and conductivity values. By analysing I-V curves and assuming a Schottky conduction mechanism the barrier height was found to be about 1.13 eV and 1.21 eV for IBI LB films without and with ZnS nanoparticles, respectively. It is thought that the presence of ZnS nanoparticles influences the barrier height at the metal-organic film interface and causes a change in electrical conduction properties of LB films.     

Electrical characterization of carbon monoxide sensitive high temperature sensor diode based on catalytic metal gate-insulator-silicon carbide structure

Field-effect gas sensors based on catalytic metal-insulator-silicon carbide (MISiC) devices are investigated. For the evaluation of the barrier height, the temperature dependence of the current-voltage (I-V) and the capacitance-voltage (C-V) characteristics of MISiC Schottky diodes were investigated in CO and O/sub 2/ atmospheres. Four methods were used to evaluate how a change in gas ambient influences the barrier height of the diode: a change of the intersection current at zero voltage in the forward direction of the I-V curve, a change of the temperature dependence in the forward direction and the reverse direction, respectively, of the I-V curve, and a change of the intersection voltage of 1/C/sup 2/ versus V plot. The four methods gave similar changes in the barrier height for the device in 8000 ppm CO and 4000 ppm O/sub 2/. The values of barrier height obtained from the I-V curves were here normalized by the ideality factor calculated from I-V measurements. The correlation between the barrier height change obtained from the I-V and the C-V measurements, respectively, is discussed regarding the ideality factor.     

Fabrication and electrical characterization of p-Cu2O/n-ZnO heterojunction

The conducting metal oxide (ZnO, Cu2O) films were used for fabrication of p-n heterojunction by rf sputtering and electrodeposition techniques respectively. The as synthesized films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV spectroscopy and electrical techniques. The electrical properties of the p-Cu2O/n-ZnO heterojunction were examined using the current-voltage measurements. The current-voltage (I-V) result showed that potential barrier was higher than the turn-on voltage, which was attributed to the presence of the interface defect states. The PN junction parameters such as ideality factor, barrier height, and series resistance were determined using conventional forward bias current-voltage characteristics. The annealing of Cu2O increase the crystallinity size and which enhance the photo current from 1.6 mA/cm2 to 3.7 mA/cm2. The annealing of respective film resulted in a decrease of these parameters with an increase in efficiency of solar cell from 0.14% to 0.3% at 350 degrees C.     

ZnO Film UV Photodetector with Enhanced Performance: Heterojunction with CdMoO4 Microplates and the Hot Electron Injection Effect of Au Nanoparticles

A novel CdMoO₄–ZnO composite film is prepared by spin‐coating CdMoO₄ microplates on ZnO film and is constructed as a heterojunction photodetector (PD). With an optimized loading amount of CdMoO₄ microplates, this composite film PD achieves a ≈18‐fold higher responsivity than pure ZnO film PD at 5 V bias under 350 nm (0.15 mW cm⁻²) UV light illumination, and its decay time shortens to half of the original value. Furthermore, Au nanoparticles are then deposited to modify the CdMoO₄–ZnO composite film, and the as‐constructed photodetector with an optimized deposition time of Au nanoparticles yields an approximately two‐fold higher photocurrent under the same condition, and the decay time reduces by half. The introduced CdMoO₄ microplates form type‐II heterojunctions with ZnO film and improve the photoelectric performance. The hot electrons from Au nanoparticles are injected into the CdMoO₄–ZnO composite film, leading to the increased photocurrent. When the light is off, the Schottky barriers formed between Au nanoparticles and CdMoO₄–ZnO composite film block the carrier transportation and accelerate the decay process of current. The study on Au‐nanoparticle‐modified CdMoO₄–ZnO composite film provides a facile method to construct ZnO film based PD with novel structure and high photoelectric performance.     

Formation and rupture of Schottky nanocontacts on ZnO nanocolumns

In this paper, the electrical transport and mechanical properties of Pt/ZnO Schottky nanocontacts have been studied simultaneously during the formation and rupture of the nanocontacts. By combining multidimensional conducting scanning force spectroscopy with appropriated data processing, the physical relevant parameters (the ideality factor, the Schottky barrier height, and the rupture voltage) are obtained. It has been found that the transport curves strongly depend on the loading force. For loading forces higher than a threshold value, the transport characteristics are similar to those of large-area Schottky contact, while below this threshold deviations from strictly thermionic emission are detected. Above the threshold, stable and reproducible Pt/ZnO nanocontacts with ideality factors of about 2 and Schottky barrier heights of around 0.45 eV have been obtained.     

Direct measurements of lateral variations of Schottky barrier height across "end-on" metal contacts to vertical Si nanowires by ballistic electron emission microscopy

Ballistic electron emission microscopy measurements on individual "end-on" Au Schottky contacts to vertical Si nanowires (NWs) indicate that the local Schottky barrier height at the contact edge is 23 ± 3 meV lower than at the contact center. Finite-element electrostatic simulations suggest that this is due to a larger interface electric field at the contact edge resulting from (equilibrium) positive charge in Si/SiO(2) interface states near the Au/NW contact, induced by local band bending due to the high work function Au film.     

Metal/nonpolar <Emphasis Type="Italic">m</Emphasis>-plane ZnO contacts with and without thin Al<Subscript>2</Subscript>O<Subscript>3</Subscript> interlayer deposited by atomic layer deposition

Using the temperature dependent current–voltage (I–V) measurements, the electrical properties of Au/nonpolar m-plane ZnO Schottky diodes with an Al₂O₃ interlayer prepared by atomic layer deposition (ALD) was investigated. With an Al₂O₃ interlayer, it was found to have higher barrier heights and higher rectifying ratio. Modified Richardson plots produced effective Richardson constants of 30.0 and 37.6 Acm^?2K^?2 for the samples with and without Al₂O₃ interlayer, respectively, which are similar to the theoretical value of 32.0 Acm^??2K^??2 for n-ZnO. Scanning transmission electron microscope (STEM) results showed that the oxygen-contained layer on ZnO surface degraded the film quality of subsequently deposited Al₂O₃ layer. In addition, the inter-diffusion of Au and Al atoms into ZnO subsurface region also modulated the electrical properties of Au/ZnO contacts.     

Preparation of ZnO nanoparticles using electrodeposition and co-precipitation techniques for dye-sensitized solar cells applications

Zinc oxide thin films have been successfully prepared by co-precipitation and electrodeposition methods onto Fluorinated tin oxide substrate using zinc nitrate aqueous solutions at various bath temperatures (25–75 °C). The deposition of electrodeposition method was conducted using both using linear sweep voltammetry and Chronoamperometric techniques. The effects of solution composition, agitation and bath temperature on the electrochemical measurements and ZnO film characteristics were fully analyzed. The findings reveal that temperature and nitrate ion concentration have a strong promoting effect on ZnO film formation. Moreover, the obtained powders were investigated by X-ray diffraction, Field emission scanning electron microscopy and UV–Vis Spectroscopy. Structural characterization by X-ray diffraction indicates the formation of ZnO phase and the deposited film exhibits the Zincite structure with crystallite size around 51 nm. The photovoltaic performance of dye-sensitized solar cells based on both ZnO prepared by co-precipitation and electrodeposition methods was investigated. A power conversion efficiency (η) of 3.5 % was achieved for the DSSC with co-precipitation ZnO, which is higher than that of the cell with electrodeposition ZnO (2.5 %). Explanations are substantiated by incident photon to electron conversion efficiency curves.     

STM"接触"式测量中的整流效应

在利用扫描隧道显微镜(STM)对Ag-TCNQ薄膜进行"接触"式的I-V特性测量中,发现由于接触势垒引起的整流效应.这为有机分子在电子学的应用方面,提供一种新的思路,从而设计新的有机电子器件.     

Immobilizing ZnO nanoparticles to porous film by occlusion electrosynthesis for photoelectrochemical cells

In this letter, highly porous ZnO film with a considerable thickness about 35 μm was prepared by electrodeposition with ZnO nanoparticles dispersed in ZnO electrolyte, which was also known as occlusion electrosynthesis (OE). The ZnO/CdS photoelectrode with the ZnO film prepared by OE showed far more superior optical and photoelectrochemical performance to that with the ZnO film prepared by electrodeposition without ZnO nanoparticles dispersed in electrolyte (ED). Since ZnO nanoparticles can be separately prepared, optimized and tailored prior to OE process, it is expected to prepare porous ZnO film by OE with various morphology and properties for specific application at low temperature, especially for flexible devices.     

3-巯基-1-丙烷磺酸钠复配添加剂对铜电沉积的作用及机理

3-巯基-1-丙烷磺酸钠(MPS)、聚乙二醇(PEG)、Cl-(MPS-PEG-Cl)添加剂组合硫酸盐镀液常用于超大集成电路铜的超等角填充。采用极化曲线和电化学交流阻抗谱(EIS)研究了酸性硫酸铜镀液中MPS与PEG和Cl-于一定浓度组合下对Cu电沉积的影响。极化曲线和EIS结果一致表明,MPS与PEG和Cl-之间都存在协同作用,MPS-PEG阻化而MPS-Cl和MPS-PEG-Cl促进Cu的电沉积;低电位下,MPS和Cl-,Cu+/Cu2+形成的中间产物吸附于电极表面;MPS阻化Cu的电沉积,但与Cl-一起有协同作用,在超等角填充中起促进作用,大于阻化作用,这种促进作用源于MPS和Cl-的配位反应。