Effect of RF power on the properties of transparent conducting zirconium-doped zinc oxide films prepared by RF magnetron sputtering

Transparent and conducting zirconium-doped zinc oxide films with high transparency and relatively low resistivity have been successfully prepared by radio frequency （RF） msgnetron sputtering at room temperature, The RF power is varied from 75 to 150 W. At first the crystallinity and conductivity of the film are improved and then both of them show deterioration with the increase of the RF power, The lowest resistivity achieved is 2.07 × 10^-3Ωcm at an RF power of 100W with a Hall mobility of 16cm^2V^-1s^-1 and a carrier concentration of 1.95 × 10^20 cm^-3. The films obtained are polycryetalline with a hexagonal structure and a preferred orientation along the c-axis, All the films have a high transmittance of approximately 92% in the visible range. The optical band gap is about 3.33 eV for the films deposited at different RF powers.

THE BAND STRUCTURE AND WORK FUNCTION OF TRANSPARENT CONDUCTING ALUMINUM AND MANGANESE CO-DOPED ZINC OXIDE FILMS

Al and Mn co-doped-ZnO films have been prepared at room temperature by DC reacti ve magnetron sputtering technique. The optical absorption coefficient, apparent and fundamental band gap, and work function of the films have been investigated using optical spectroscopy, band structure analyses and ultraviolet photoelectro n spectroscopy (UPS). ZnO films have direct allowed transition band structure, w hich has been confirmed by the character of the optical absorption coefficient. The apparent band gap has been found directly proportional to N2/3, showing that the effect of Burstein-Moss shift on the band gap variations dominates over the many-body effect. With only standard cleaning protocols, the work function of ZnO: (Al, Mn) and ZnO: Al films have been measured to be 4.26 and 4.21eV, respec tively. The incorporation of Mn element into the matrix of ZnO, as a relatively deep donor, can remove some electrons from the conduction band and deplete the d ensity of occupied states at the Fermi energy, which causes a loss in measured p hotoemission intensity and an increase in the surface work function. Based on th e band gap and work function results, the energy band diagram of the ZnO: (Al, M n) film near its surface is also given.

Density functional theory analysis of electronic structure and optical properties of La-doped Cd_2SnO_4 transparent conducting oxide

The electronic structural, effective masses of carriers, and optical properties of pure and La-doped Cd2SnO4 are calculated by using the first-principles method based on the density functional theory. Using the GGA＋U method, we show that Cd2SnO4 is a direct band-gap semiconductor with a band gap of 2.216 eV, the band gap decreases to 2.02 eV and the Fermi energy level moves to the conduction band after La doping. The density of states of Cd2SnO4 shows that the bottom of the conduction band is composed of Cd 5s, Sn 5s, and Sn 5p orbits, the top of the valence band is composed of Cd 4d and O 2p, and the La 5d orbital is hybridized with the O 2p orbital, which plays a key role at the conduction band bottom after La doping. The effective masses at the conduction band bottom of pure and La-doped Cd2SnO4 are 0.18m0 and 0.092m0, respectively, which indicates that the electrical conductivity of Cd2SnO4 after La doping is improved. The calculated optical properties show that the optical transmittance of La-doped Cd2SnO4 is 92%, the optical absorption edge is slightly blue shifted, and the optical band gap is increased to 3.263 eV. All the results indicate that the conductivity and optical transmittance of Cd2SnO4 can be improved by doping La.

Effects of Atomic Oxygen Irradiation on Transparent Conductive Oxide Thin Films

Transparent conductive oxide （TCO） thin film is a kind of functional material which has potential applications in solar cells and atomic oxygen （AO） resisting systems in spacecrafts. Of TCO, ZnO：Al （ZAO） and In2O3：Sn （ITO） thin films have been widely used and investigated. In this study, ZAO and ITO thin films were irradiated by AO with different amounts of fluence. The as-deposited samples and irradiated ones were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and Hall-effect measurement to investigate the dependence of the structure, morphology and electrical properties of ZAO or ITO on the amount of fluence of AO irradiation. It is noticed that AO has erosion effects on the surface of ZAO without evident influences upon its structure and conductive properties. Moreover, as the amount of AO fluence rises, the carrier concentration of ITO decreases causing the resistivity to increase by at most 21.7%.

Preparation and Characterization of Transparent Conductive Zinc Doped Tin Oxide Thin Films Prepared by Radio-frequency Magnetron Sputtering

High transparent and conductive thin films of zinc doped tin oxide （ZTO） were deposited on quartz substrates by the radio-frequency （RF） magnetron sputtering using a 12 wt% ZnO doped with 88 wt% SnO2 ceramic target.The effect of substrate temperature on the structural,electrical and optical performances of ZTO films has been studied.X-ray diffraction （XRD） results show that ZTO films possess tetragonal rutile structure with the preferred orientation of （101）.The surface morphology and roughness of the films was investigated by the atomic force microscope （AFM）.The electrical characteristic （including carrier concentration,Hall mobility and resistivity） and optical transmittance were studied by the Hall tester and UV- VIS,respectively.The highest carrier concentration of -1.144×1020 cm-3 and the Hall mobility of 7.018 cm2（V ·sec）-1 for the film with an average transmittance of about 80.0% in the visible region and the lowest resistivity of 1.116×10-2 Ω·cm were obtained when the ZTO films deposited at 250 oC.

Dopant-Tunable Ultrathin Transparent Conductive Oxides for Efficient Energy Conversion Devices

Ultrathin film-based transparent conductive oxides(TCOs)with a broad work function(WF)tunability are highly demanded for e cient energy conversion devices.However,reducing the film thickness below 50 nm is limited due to rapidly increasing resistance;furthermore,introducing dopants into TCOs such as indium tin oxide(ITO)to reduce the resistance decreases the transparency due to a trade-o between the two quantities.Herein,we demonstrate dopant-tunable ultrathin(≤50 nm)TCOs fabricated via electric field-driven metal implantation(m-TCOs;m=Ni,Ag,and Cu)without com-promising their innate electrical and optical properties.The m-TCOs exhibit a broad WF variation(0.97 eV),high transmittance in the UV to visible range(89–93%at 365 nm),and low sheet resistance(30–60Ωcm-2).Experimental and theoretical analyses show that interstitial metal atoms mainly a ect the change in the WF without substantial losses in optical transparency.The m-ITOs are employed as anode or cathode electrodes for organic light-emitting diodes(LEDs),inorganic UV LEDs,and organic photovoltaics for their universal use,leading to outstanding performances,even without hole injection layer for OLED through the WF-tailored Ni-ITO.These results verify the proposed m-TCOs enable e ective carrier transport and light extraction beyond the limits of traditional TCOs.

The properties of transparent conducting molybdenum-doped ZnO films grown by radio frequency magnetron sputtering

Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency（RF） magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis.The resistivity first decreases and then increases with the increase in MoO3 content.The lowest resistivity achieved is 9.2 × 10^-4.cm,with a high Hall mobility of 30 cm^2.V-1.s-1 and a carrier concentration of 2.3×10^20 cm^-3 at an MoO3 content of 2 wt%.The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO3 content in the target.

Annealing time dependent structural, morphological, optical and electrical properties of RF sputtered p-type transparent conducting SnO_2/Al/SnO_2 thin films

Transparent p-type conducting SnO2/Al/SnO2 multilayer films were fabricated on quartz substrates by radio frequency(RF) sputtering using SnO2 and Al targets. The deposited films were annealed at a fix temperature of 500 °C for different time durations(1-8 h). The effect of annealing time on the structural, morphological, optical and electrical performances of SnO2/Al/SnO2 multilayer films was studied. X-ray diffraction(XRD) results show that all the p-type conducting films possess polycrystalline SnO2 with tetragonal rutile structure. Hall-effect results indicate that 500 °C for 1 h is the optimum annealing condition for p-type SnO2/Al/SnO2 multilayer films, resulting in a hole concentration of 1.14×1018 cm-3 and a low resistivity of 1.38 ?·cm, respectively. The optical transmittance of the p-type SnO2/Al/SnO2 multilayer films is above 80% within annealing time range of 1-8 h, showing maximum for the films annealed for 1 h.

Reliability of transparent conductive oxide in ambient acid and implications for silicon solar cells

Transparent conductive oxide(TCO)films,known for their role as carrier transport layers in solar cells,can be adversely affected by hydrolysis products from encapsulants.In this study,we explored the morphology,optical-electrical properties,and deterioration mechanisms of In2O3-based TCO films under acetic acid stress.A reduction in film thickness and carrier concentration due to acid-induced corrosion was observed.X-ray photoelectron spectroscopy and inductively coupled plasma emission spectrometry analyses revealed that TCOs doped with less-reactive metals exhibited enhanced corrosion resistance.The efficiency of silicon heterojunction(SHJ)solar cells with tin-doped indium oxide,titanium-doped indium oxide,and zinc-doped indium oxide films decreased by 10%,26%,and 100%,respectively,after 200h of corrosion.We also found that tungsten-doped indium oxide could effectively safeguard SHJ solar cells against acetic acid corrosion,which offers a potential option for achieving long-term stability and lower levelized cost of solar cell systems.This research provides essential insights into selecting TCO films for solar cells and highlights the implications of ethylene-vinyl acetate hydrolysis for photovoltaic modules.

The properties of transparent conducting molybdenum-doped ZnO films grown by radio frequency magnetron sputtering

Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency(RF) magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis.The resistivity first decreases and then increases with the increase in MoO3 content.The lowest resistivity achieved is 9.2 × 10-4.cm,with a high Hall mobility of 30 cm2.V-1.s-1 and a carrier concentration of 2.3×1020 cm-3 at an MoO3 content of 2 wt%.The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO3 content in the target.

A comparison of transmittance properties between ZnO∶Al films for transparent conductors for solar cells deposited by sputtering of AZO and cosputtering of AZO/ZnO

Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire (002) and glass substrates by two different sputtering techniques radio frequency magnetron cosputtering of AZO and ZnO targets and sputtering of an AZO target. The dependence of the photoluminescence (PL) and transmittance properties of the AZO films deposited by cosputtering and sputtering on the AZO/ZnO target power ratio, R and the O2/Ar flow ratio, r were investigated, respectively. Only a deep level emission peak appears in the PL spectra of cosputtered AZO films whereas both UV emission and deep level emission peaks are observed in the PL spectra of sputtered AZO films. The absorption edges in the transmittance spectra of the AZO films shift to the lower wavelength region as R and r increase. Effects of crystallinity, surface roughness, PL on the transmittance of the AZO films were also explained using the X-ray diffraction (XRD), atomic force microscopy (AFM), and PL analysis results.

Enhanced light extraction of GaN-based light-emitting diodes with periodic textured SiO_2 on Al-doped ZnO transparent conductive layer

We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent throughpore anodic aluminum oxide（AAO） membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 m A and 56% at 100 m A compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage.

Influence of the sputtering pressure on the properties of transparent conducting zirconium-doped zinc oxide films prepared by RF magnetron sputtering

Transparent conducting zirconium-doped zinc oxide films with high transparency and relatively low resistivity have been successfully prepared on water-cooled glass substrate by radio frequency magnetron sputtering at room temperature. The Ar sputtering pressure was varied from 0.5 to 3 Pa. The crystallinity increases and the electrical resistivity decreases when the sputtering pressure increases from 0.5 to 2.5 Pa. The cystallinity decreases and the electrical resistivity increases when the sputtering pressure increases from 2.5 to 3 Pa. When the sputtering pressure is 2.5 Pa, it is obtained that the lowest resistivity is 2.03 x 10^-3Ω .cm with a very high transmittance of above 94%. The deposited films are polycrystalline with a hexagonal structure and a preferred orientation perpendicular to the substrate.

Influence of the distance between target and substrate on the properties of transparent conducting Al-Zr co-doped zinc oxide thin films

Highly transparent and conducting Al-Zr co-doped zinc oxide （ZAZO） thin films were successfully prepared on glass substrate by direct current （DC） magnetron sputtering at room temperature. The distance between target and substrate was varied from 45 to 70 mm. All the deposited films are polycrystalline with a hexagonal structure and have a preferred orientation along the c-axis perpendicular to the substrate. The crystallinity increases obviously and the electrical resistivity decreases when the distance between target and substrate decreases from 70 to 50 mm. However, as the distance decreases further, the crystallinity decreases and the electrical resistivity increases. When the distance between target and substrate is 50 ram, it is found that the lowest resistivity is 6.9 × 10^-4Ω cm. All the deposited films show a high average transmittance of above 92% in the visible range.

Structural and Physical Property Analysis of ZnO-SnO_2—In_2O_3—Ga_2O_3 Quaternary Transparent Conducting Oxide System

The increasing demand in the diverse device applications of transparent conducting oxides （TCOs） requires synthesis of new TCOs of n- or p-type conductivity. This article is about materials engineering of ZnO-SnO2- In2O3-Ga2O3 to synthesize powders of the quaternary compound Zn2-xSn1-xlnxGaxO4-δ in the stoichiometry of x = 0.2, 0.3, and 0.4 by solid state reaction at 1275℃. Lattice parameters were determined by X-ray diffraction （XRD） technique and solubility of In3＋ and Ga3＋ in spinel Zn2SnO4 was found at 1275℃. The solubility limit of In3＋ and Ga3＋ in Zn2SnO4 is found at below x = 0.4. The optical transmittance approximated by the UV-Vis reflectance spectra showed excellent characteristics while optical band gap was consistent across 3.2 eV with slight decrease along increasing x value. Carrier mobility of the species was considerably higher than the older versions of zinc stannate spinel co-substitutions whereas the carrier concentrations were moderate.

Fluorine-Doped Tin Oxide Thin Films Deposition by Sol-Gel Technique

In the present work, undoped (SnO2) and fluorine-doped tin oxide (FTO) thin films were prepared by sol-gel process using a solution composed of (SnCl2, H2O), (NH4F), and ethanol mixture. The fluorine concentration effect on structural, optical and electrical properties of SnO2 films is investigated. The electrical properties of FTO films prepared by sol gel remain relatively lower than the ones deposited by other techniques. In present paper, we try to elucidate this difference. Films composition and the FTIR analysis, of films and formed precipitate during film growth, indicate that few amounts of fluorine are incorporated in SnO2 network, most of fluorine atoms remain in the solution. The films resistivity is reduced from 1.1 Ω·cm for undoped films to 3 × 10-2 Ω·cm for 50 wt.% doped FTO, but remains higher than the reported ones in the literature. This high resistivity is explained in terms of fluorine bonding affinity in the solution.

铟锡氧(ITO)和氟锡氧(FTO)透明导电薄膜的表征与分析

本文以射频(RF)磁控溅射方法制备的ITO薄膜和购置的ITO及FTO薄膜为研究对象,通过紫外可见分光光度计表征薄膜样品的透射率,结果表明ITO和FTO薄膜均展现出良好的光学透过率。采用扫描电子显微镜(SEM)观察薄膜样品的表面形貌,所有薄膜样品的表面较为均匀。通过X射线光电子能谱仪(XPS)表征薄膜样品表面的元素、组成、价态和电子态信息,结果表明制备方式与退火处理等因素影响了薄膜样品表面的元素组成与价态,这些信息与薄膜的电学和光学性能具有一定的关联。上述研究结果可以为新型透明导电薄膜的设计和性能提升提供参考。

Flexible transparent conductive film based on silver nanowires and reduced graphene oxide

Silver nanowires(Ag NWs)with diameter of 90—150 nm and length of 20—50μm were successfully synthesized by a polyol process.Graphene oxide(GO)was prepared by Hummers method,and was reduced with strong hydrazine hydrate at room temperature.The flexible transparent conductive films(TCFs)were fabricated using the mixed cellulose eater(MCE)as matrix and Ag NWs and reduced graphene oxide(r GO)as conductive fillers by the improved vacuum filtration process.Then,the optical,electrical and mechanical properties of the Ag NWs-r GO films were investigated.The results show that for the Ag NWs-r GO film produced with the deposition densities of Ag NWs and r GO as110 mg·m^(-2) and 55 mg·m^(-2),the optical transmission at 550 nm is 88.4%with Rs around 891Ω·sq^(-1),whereas the optical transmission for the Ag NWs-r GO film with deposition densities of Ag NWs and r GO of 385 mg·m^(-2) and 55 mg·m^(-2) is79.0%at 550 nm with Rs around 9.6Ω·sq^(-1).There is little overt increase in Rs of the Ag NWS-r GO film after tape tests for 200 times.The bending test results indicate that the change in Rs of Ag NWs-MCE film is less than 2%even after200 cycles of compressive or tensile bending.The excellent mechanical properties of the Ag NWs-r GO film can be attributed to the burying of Ag NWs and r GO at the surface of MCE.

Transparent conductive reduced graphene oxide thin films produced by spray coating

Reduced graphene oxide thin films were fabricated on quartz by spray coating method using a stable dispersion of reduced graphene oxide in N,N-Dimethylformamide.The dispersion was produced by chemical reduction of graphene oxide,and the film thickness was controlled with the amount of spray volume.AFM measurements revealed that the thin films have near-atomically flat surface.The chemical and structural parameters of the samples were analyzed by Raman and XPS studies.It was found that the thin films show electrical conductivity with good optical transparency in the visible to near infrared region.The sheet resistance of the films can be significantly reduced by annealing in vacuum and reach 58 k?with a light transmittance of 68.69%at 550 nm.The conductive transparent properties of the reduced graphene oxide thin films would be useful to develop flexible electronics.