Influence of Zr(50)Cu(50) thin film metallic glass as buffer layer on the structural and optoelectrical properties of AZO films

Aluminum-doped ZnO(AZO) thin films with thin film metallic glass of Zr(50)Cu(50) as buffer are prepared on glass substrates by the pulsed laser deposition. The influence of buffer thickness and substrate temperature on structural, optical, and electrical properties of AZO thin film are investigated. Increasing the thickness of buffer layer and substrate temperature can both promote the transformation of AZO from amorphous to crystalline structure, while they show(100)and(002) unique preferential orientations, respectively. After inserting Zr(50)Cu(50) layer between the glass substrate and AZO film, the sheet resistance and visible transmittance decrease, but the infrared transmittance increases. With substrate temperature increasing from 25℃ to 520℃, the sheet resistance of AZO(100 nm)/Zr(50)Cu(50)(4 nm) film first increases and then decreases, and the infrared transmittance is improved. The AZO(100 nm)/Zr(50)Cu(50)(4 nm) film deposited at a substrate temperature of 360℃ exhibits a low sheet resistance of 26.7 ?/, high transmittance of 82.1% in the visible light region, 81.6% in near-infrared region, and low surface roughness of 0.85 nm, which are useful properties for their potential applications in tandem solar cell and infrared technology.

Dependence of Structural and Optoelectrical Properties on the Composition of Electron Beam Evaporated Zn_xCd_(1-x)S Thin Films

Thin films of ZnxCd1-xS have been prepared by electron beam evaporation of a mixture of ZnS & CdS powders. The films are deposited onto sodalime glass slides under similar conditions.The composition of the films is varied from CdS to ZnS (x=0 to 1). The films show a regular change in color from toner red to orange yellow as Zn concentration increases to maximum.These films are characterized for their optical, electricaI and structural properties. The bandgap value of ZnxCd1-xS films is found to vary linearIy from 2.20 eV to 3.44 eV with change in the x value from 0 to 1. The resistivity of these films is in the range of 171.0 Ωcm to 5.5× 106Ωcm for x=0~0.6. All the samples show cubic structure after annealing in air at 250℃ for 40 min.The lattice constant ao varies from 0.5884 nm to 0.54109 nm linearly.

Substrate Evolution to Microstructural and Optoelectrical Properties of Evaporated CdS Thin Films Correlated with Elemental Composition

A typical high-e fficiency solar cell device needs the best lattice matching between different constituent layers to mitigate the open-circuit voltage loss. In the present work, the physical properties of CdS thin films are investigated where films with 100 nm thickness were fabricated on the different types of substrates viz. soda–lime glass, indium-doped tin oxide(ITO)-and fl uorine-doped tin oxide(FTO)-coated glass substrates, and silicon wafer using electron beam evaporation. The X-ray diffraction patterns confirmed that deposited thin films showed cubic phase and had(111) as predominant orientation where the structural parameters were observed to be varied with nature of substrates. The ohmic behaviour of the CdS films was disclosed by current–voltage characteristics, whereas the scanning electron microscopy micrograph revealed the uniform deposition of the CdS films with the presence of round-shaped grains. The elemental analysis confirmed the CdS films deposition where the Cd/S weight percentage ratio was changed with nature of substrates. The direct energy band gap was observed in the 1.63–2.50 eV range for the films grown on different substrates. The investigated properties of thin CdS layers demonstrated that the selection of substrate(in terms of nature) during device fabrication plays a crucial role.

Structure and optoelectrical properties of transparent conductive MGZO films deposited by magnetron sputtering

The transparent conductive Mg-Ga co-doped Zn O(MGZO) films were prepared by radio-frequency(RF) magnetron sputtering. The influence of substrate temperature on the structural and optoelectrical properties of the films is studied. The results show that all the films possess a preferential orientation along the(002) plane. With the increase of substrate temperature, the structure and optoelectrical properties of the films can be changed. When substrate temperature is 300 ℃, the deposited film exhibits the best crystalline quality and optoelectrical properties, with the minimum micro strain of 1.09×10^(-3), the highest average visible transmittance of 82.42%, the lowest resistivity of 1.62×10^(-3) Ω·cm and the highest figure of merit of 3.18×10~3 Ω^(-1)·cm^(-1). The optical bandgaps of the films are observed to be in the range of 3.342—3.545 eV. The refractive index dispersion curves obey the Sellmeier's dispersion model.

A new perspective on optoelectric conversion in conjugated polymers

Photoexcitation of a neutral soliton will create a polaron and a charged soliton. According to a tight-binding model and a nonadiabatic method, we investigate the dynamical process of these two photogenerated charge carriers in an external electric field. It is found that the polaron and the soliton can pass through each other, which excludes the possibility of carrier recombination that usually occurs in existing organic solar cells. The results indicate a more efficient way to realize the optoelectric conversion by photoexciting polymer materials with soliton defects. On the other hand, it is found that solitons take on greater stability than polarons during collision.

Design of Optoelectric Detection Circuit for Difference Absorption Gas Sensor

Since the gas infrared absorption spectrum source intensity of several in a thousand, it is even less linewidth is only several nanometers occupying the than the noise of light source. The signal of gas absorption is submerged in the noise, so it is impossible to measure the concentration of gas with spectrum absorption directly. According to the principle and parameters of difference absorption system of CH4 gas, a detection circuit consisted of the lock-in amplifier is designed. The experiment results indicated that the detection circuit can satisfy the demand of the whole system, and the limit concentration is 150×10^-6.

Logic and in-memory computing achieved in a single ferroelectric semiconductor transistor

Exploring materials with multiple properties who can endow a simple device with integrated functionalities has attracted enormous attention in the microelectronic field. One reason is the imperious demand for processors with continuously higher performance and totally new architecture. Combining ferroelectric with semiconducting properties is a promising solution. Here, we show that logic, in-memory computing, and optoelectrical logic and non-volatile computing functionalities can be integrated into a single transistor with ferroelectric semiconducting α-In2Se3 as the channel. Two-input AND, OR, and nonvolatile NOR and NAND logic operations with current on/off ratios reaching up to five orders, good endurance(1000 operation cycles), and fast operating speed(10μs) are realized. In addition, optoelectrical OR logic and non-volatile implication(IMP) operations, as well as ternary-input optoelectrical logic and inmemory computing functions are achieved by introducing light as an additional input signal. Our work highlights the potential of integrating complex logic functions and new-type computing into a simple device based on emerging ferroelectric semiconductors.

Fabrication of high-quality silver nanowire conductive film and its application for transparent film heaters

Here,we report a facile method to produce pure silver nanowires(Ag NWs)with high yield.A highly conductive dispersant was used to ensure uniform dispersion of the Ag NWs.Without any posttreatment,the Ag NW networks,deposited on flexible substrates,showed excellent optoelectrical performance owing to minimal junction resistance between the Ag NWs.To explore their potential in flexible optoelectronic devices,a transparent film heater was constructed based on the present Ag NW networks.The heater could achieve rapid response at low input voltage and reach a relatively high temperature in a short response time.Since this high-quality Ag NW film exhibits relatively low production costs and fast production time,it may have value for future electronic industry applications.

Dynamic optoelectric trapping and deposition of multiwalled carbon nanotubes

In the path toward the realization of carbon nanotube(CNT)-driven electronics and sensors,the ability to precisely position CNTs at well-defined locations remains a significant roadblock.Highly complex CNT-based bottom–up structures can be synthesized if there is a method to accurately trap and place these nanotubes.In this study,we demonstrate that the rapid electrokinetic patterning(REP)technique can accomplish these tasks.By using laser-induced alternating current(AC)electrothermal flow and particle–electrode forces,REP can collect and maneuver a wide range of vertically aligned multiwalled CNTs(from a single nanotube to over 100 nanotubes)on an electrode surface.In addition,these trapped nanotubes can be electrophoretically deposited at any desired location onto the electrode surface.Apart from active control of the position of these deposited nanotubes,the number of CNTs in a REP trap can also be dynamically tuned by changing the AC frequency or by adjusting the concentration of the dispersed nanotubes.On the basis of a calculation of the stiffness of the REP trap,we found an upper limit of the manipulation speed,beyond which CNTs fall out of the REP trap.This peak manipulation speed is found to be dependent on the electrothermal flow velocity,which can be varied by changing the strength of the AC electric field.

Regulation of morphology and visible light-driven photocatalysis of WO_(3)nanostructures by changing pH

The controlled preparation of hexagonal tungsten trioxide(h-WO_(3))nanostructures was achieved by adjusting the pH of the precursor solution.The effect of the pH on the morphology,elemental composition,and photocatalytic performance of the samples was characterized via X-ray diffraction(XRD),scanning electron microscopy,energy dispersive X-ray spectroscopy,and Raman spectroscopy.Ultraviolet-visible(UV-Vis)spectra were used to evaluate the absorbance and the photocatalytic performance of methylene blue.Photoluminescence(PL),electrochemical impedance spectroscopy,photocurrent response and Brunauer-Emmett-Teller(BET)were used to study the optical properties,electrical performance,and specific surface area of the WO_(3)-nanostructures,respectively.The results indicate that the WO_(3) nanorods prepared at pH=1.0 exhibit the highest photocatalytic performance(87.4%in 1 h),whereas the WO_(3) nanoblocks prepared at p H=3.0 show the lowest.The photocatalytic performance of the one dimensional(1 D)-nanorods can be attributed to their high specific surface area and charge transfer ability.The h-WO_(3) nanostructures were synthesized via a simple method and without a capping agent.They show an excellent photocatalytic performance,which is promising for their application in environment purification.

Transition metal dichalcogenides (TMDCs) heterostructures: Optoelectric properties

Transition metal dichalcogenides(TMDCs)have suitable and adjustable band gaps,high carrier mobility and yield.Layered TMDCs have attracted great attention due to the structure diversity,stable existence in normal temperature environment and the band gap corresponding to wavelength between infrared and visible region.The ultra-thin,flat,almost defect-free surface,excellent mechanical flexibility and chemical stability provide convenient conditions for the construction of different types of TMDCs heterojunctions.The optoelectric properties of heterojunctions based on TMDCs materials are summarized in this review.Special electronic band structures of TMDCs heterojunctions lead to excellent optoelectric properties.The emitter,p-n diodes,photodetectors and photosensitive devices based on TMDCs heterojunction materials show excellent performance.These devices provide a prototype for the design and development of future high-performance optoelectric devices.