Conductive SnO2 Research Articles

Enhanced Electronic Properties of SnO2 via Electron Transfer from Graphene Quantum Dots for Efficient Perovskite Solar Cells.

Tin dioxide (SnO2) has been demonstrated as an effective electron-transporting layer (ETL) for attaining high-performance perovskite solar cells (PSCs). However, the numerous trap states in low-temperature solution processed SnO2 will reduce the PSCs performance and result in serious hysteresis. Here, we report a strategy to improve the electronic properties in SnO2 through a facile treatment of the films with adding a small amount of graphene quantum dots (GQDs). We demonstrate that the photogenerated electrons in GQDs can transfer to the conduction band of SnO2. The transferred electrons from the GQDs will effectively fill the electron traps as well as improve the conductivity of SnO2, which is beneficial for improving the electron extraction efficiency and reducing the recombination at the ETLs/perovskite interface. The device fabricated with SnO2:GQDs could reach an average power conversion efficiency (PCE) of 19.2 ± 1.0% and a highest steady-state PCE of 20.23% with very little hysteresis. Our study provides an effective way to enhance the performance of perovskite solar cells through improving the electronic properties of SnO2.

SnO2-Supported Electrocatalysts on Various Conductive Fillers for PEFCs

Electrocatalyst layers in polymer electrolyte fuel cells (PEFCs) have complicated 3-dimensional microstructure, so that control and optimization of the structure are essential for higher cell performance. Carbon black supported cathode electrocatalyst is widely used, whilst carbon black support can be degraded through electrochemical oxidation on the cathode side. In this study, stable and electronic conductive Nb-doped SnO2 support deposited on conductive carbon nanotube (CNT) fillers is considered as an alternative support material for high cell performance. High initial current-voltage (I-V) characteristics and voltage cycle durability of membrane electrode assemblies (MEAs) using Nb-doped SnO2 supports deposited on CNTs are successfully demonstrated under the PEFC operational condition.

Electrochemical reduction of carbon dioxide at nanostructured SnO2/carbon aerogels: The effect of tin oxide content on the catalytic activity and formate selectivity

Electrochemical reduction of CO2 has been considered as a promising method for the production of value-added chemicals. In this work, the electrochemical reduction of CO2 to formate is carried out over novel carbon aerogel supported SnO2 nanocrystals prepared by a facile hydrothermal method. The as prepared materials exhibit good catalytic activity and high formate selectivity. It is found that the content of SnO2 plays an important role in the whole process, in which the formate is the exclusive product. At low SnO2 content the catalyst shows poor activity due to the lack of active ingredients, while at high SnO2 content it results in a dramatic decrease of the faradaic efficiency for the formate because of the blockage of part of active sites due to the agglomeration and poor conductivity of SnO2. It is also found that the optimized SnO2/CA-80 with 28.1 wt.% SnO2 leads to the best performance, offering a relatively high faradaic efficiency of ∼76% for the formate formation in 1.0 mol/L KHCO3 at −0.96 V (vs. RHE). Moreover, the above catalyst exhibits excellent stability during the control potential electrolysis for 12 h.

Sb-doped SnO2/graphene-CNT aerogels for high performance Li-ion and Na-ion battery anodes

SnO2 has been extensively explored as a potential anode material for both Li-ion (LIBs) and Na-ion batteries (SIBs). It possesses however an extremely poor electrical conductivity, making it difficult to be used as the standalone electrode. Herein, Sb-doped SnO2 (ATO) nanoparticles are in situ grown on N-doped graphene-CNT aerogels (N-GCAs) based on a facile hydrothermal self-assembly route for the first time. The ATO/N-GCA composite presents a highly porous structure along with an electrical conductivity enhanced by over two orders of magnitude through the in situ Sb doping. The composite electrode delivers an outstanding rate capability of 659mAhg−1 at 10Ag−1 with capacity retention of 73% after 1000 cycles at 1Ag−1 in LIBs. The same electrode also maintains 74% of its capacity after 500 cycles in SIBs, confirming a promising anode for both rechargeable batteries. We reveal distinct reaction kinetics and phase transition behaviors of ATO electrodes in different rechargeable batteries. The lithiation of ATO ensues consecutive conversion and alloying reactions while only the conversion reaction takes place during sodiation. Furthermore, the diffusion coefficient of Na+ ion in ATO is nine orders of magnitude lower than that of Li+ ions. The enhanced electrical conductivity of SnO2 by Sb doping dominates the capacity enhancements in LIBs whereas the mesoporous structure of hybrid aerogel plays a more important role in enhancing the Na+ ion storage performance. These new findings may offer insights into the relatively poor performance of SIBs and will help proper structural design of high performance bi-functional anodes for alkali metal ion batteries.

Synthesis of metallic silver nanoparticles decorated mesoporous SnO 2 for removal of methylene blue dye by coupling adsorption and photocatalytic processes

Abstract Herein, we report a successful route for synthesis SnO2 and SnO2 decorated with 5 wt% metallic silver nanoparticles by sol-gel route using PVP as structure and pore directing agent. X-ray diffraction [XRD], N2-adsorption-desorption isotherm, diffuse reflectance spectra [DRS], Photoluminescence [PL] and high resolution transmission electron microscope [HRTEM] were selected to give a clear clue on the physicochemical features of the prepared nanoparticles. Homogeneous dispersion of metallic silver nanoparticles on the surface and the pore wall of SnO2 are accompanied by creation of various types of pores ranging from supermicropores to wide mesoporous system that results in remarkable increase in surface area, pore volume and C-BET constant by about 50%. This situation can explain the exceptional increase in the amount of dye adsorbed under dark conditions. Both adsorption and photocatalytic reactivity of silver decorated SnO2 are responsible by nearly the same extent for removal of methylene blue dye. COD experimental result confirms the degradation of the majority of methylene blue dye. The scavenger study indicates that all charge carrier and reactive radicals contribute by the same extent in case of pure SnO2. However, the positive holes and hydroxyl radicals are the predominant reactive species on Ag/SnO2. This result confirms the electron transfer from SnO2 conduction band to Ag Fermi level, so, the positive holes and the hydroxyl radical are more available to oxidize the organic pollutants. A new photocatalyst can be developed as an economically feasible and environmentally friendly method to mineralize wastewater from organic pollutants.

Transport, structural and optical properties of SnO2 transparent semiconductor thin films alloyed with chromium: carrier type conversion

In this work, tin oxide thin films alloyed with chromium up to 50 at.% were prepared via spray pyrolysis method on preheated glass substrates of 480 °C, and the effect of Cr on the structural, optical, electrical and thermo-electrical properties of SnO2:Cr thin films was studied. The results show that all the films grow in polycrystalline form with tetragonal rutile structure. The lattice volume of SnO2:Cr films was found to be minimum at the critical Cr concentration of 15% indicating to two different mechanisms for Cr addition: For low Cr concentration (<15%) substitutional doping is the involving mechanism, while for more Cr addition, interstitial doping is the dominant one in the studied films. Cr addition in SnO2 films results in reduction of crystallite size, transparency and band-gap, and also varies resistivity and carrier concentration. The remarkable effect of Cr addition was revealed as achieving p-type conductivity in SnO2:Cr films with Cr content ranging 5–15%.

Sputtering deposition of transparent conductive F-doped SnO2 (FTO) thin films in hydrogen-containing atmosphere

Abstract F-doped SnO 2 (FTO) thin films have been prepared by sputtering SnO 2 -SnF 2 target in Ar+H 2 atmosphere. The effects of H 2 /Ar flow ratio on the structural, electrical and optical properties of the films were investigated at two substrate temperatures of 150 and 300 °C and two base pressures of 3.5×10 −3 and 1.5×10 −2 Pa. The results show that introducing H 2 into sputtering atmosphere can lead to the formation of a FTO film with a (101) preferred orientation and produce oxygen vacancy ( V O ) at lower H 2 /Ar flow ratios, but SnO phase at higher H 2 /Ar flow ratios in the films. Accordingly, the resistivity of the films first decreases and then increases, but the transmittance decreases continuously with increasing H 2 /Ar flow ratio. When H 2 /Ar flow ratio is increased above a certain value, more amorphous SnO phase forms in the films, resulting in a big decrease in conductivity, transmittance, and band gap ( E g ). Increasing substrate temperature can increase the Hall mobility due to the improvement of film crystallinity, but decrease the carrier concentration due to outward-diffusion of fluorine in the films. At a base pressure of 3.5×10 −3 Pa, high substrate temperature (300 °C) can hinder the formation of SnO and thus improve the transparent conductive properties of the films. At a base pressure of 1.5×10 −2 Pa, the range of H 2 /Ar flow ratio for forming the SnO 2 phase and hence for obtaining high transparent conductive FTO films is widened at both substrate temperatures of 150 and 300 °C.

Electronically Conductive Sb-doped SnO2 Nanoparticles Coated LiNi0.8Co0.15Al0.05O2 Cathode Material with Enhanced Electrochemical Properties for Li-ion Batteries

The LiNi0.8Co0.15Al0.05O2 (NCA) cathode material is modified by electronically conductive antimony-doped tin oxide (ATO) nanoparticles via a facile wet chemical process. As observed by scanning and transmission electron microscopy, the ATO nanoparticles are homogeneously coated on the surface of NCA material. Thus-obtained ATO-coated NCA (ATO-NCA) material delivers a high discharge capacity of 145mAhg−1 at the current rate of 5C, which is significantly higher than that of pristine NCA material (135mAhg−1). Moreover, the capacity retention of ATO-NCA material is 91.70% after 200 cycles at the current rate of 1C and 60°C. In contrast, the pristine NCA only maintains 70.89% of its initial capacity after the same cycles. The substantially improved cyclability and rate capability are mainly attributed to the ATO coating layer, which can not only enhance the electron transport but also effectively restrain the side reactions between the NCA material and the electrolyte. More specifically, X-ray diffraction and photoelectron spectroscopy reveal that the ATO coating layer can restrain the Li+/Ni2+ disordering and the growth of SEI layer of NCA material, which are responsible for the improved cycling stability, especially at elevated temperatures.

A study of structural, electrical, and optical properties of p-type Zn-doped SnO2 films versus deposition and annealing temperature

This study presents a detailed investigation of the structural, electrical, and optical properties of p-type Zn-doped SnO2 versus the deposition and annealing temperature. Using a direct-current (DC) magnetron sputtering method, p-type transparent conductive Zn-doped SnO2 (ZTO) films were deposited on quartz glass substrates. Zn dopants incorporated into the SnO2 host lattice formed the preferred dominant SnO2 (1 0 1) and (2 1 1) planes. X-ray photoelectron spectroscopy (XPS) was used for identifying the valence state of Zn in the ZTO film. The electrical property of ZTO films changed from n-type to p-type at the threshold temperature of 400 °C, and the films achieved extremely high conductivity at the optimum annealing temperature of 600 °C after annealing for 2 h. The best conductive property of the film was obtained on a 10 wt% ZnO-doped SnO2 target with a resistivity, hole concentration, and hole mobility of 0.22 Ω · cm, 7.19 × 1018 cm−3, and 3.95 cm2 V−1 s−1, respectively. Besides, the average transmission of films was >84%. The surface morphology of films was examined using scanning electron microscopy (SEM). Moreover, the acceptor level of Zn2+ was identified using photoluminescence spectra at room temperature. Current–voltage (I–V) characteristics revealed the behavior of a p-ZTO/n-Si heterojunction diode.

Transparent conductive F-doped SnO2 films prepared by RF reactive magnetron sputtering at low substrate temperature

To obtain highly transparent conductive F-doped SnO2 films by magnetron sputtering at low substrate temperatures, a new method of sputtering high-density SnF2–Sn target in Ar + O2 atmosphere was adopted in the present study. The structural, electrical, and optical properties of the films prepared were investigated as a function of O2 flux. The results indicate that the films shows SnO2 phase only at O2 flux above a critical value (0.8 sccm), and the crystallinity of SnO2 phase is improved with increasing O2 flux. The resistivity of the films steeply decreases once O2 flux is above the critical value, but it greatly increases as O2 flux is too high. Only in intermediate range of O2 flux, the films with low resistivity can be obtained. As O2 flux is above the critical value, both the transmittances in visible light range and E g of the films show steeply increase, and the PL spectra of the film show distinct emission characteristics. Furthermore, the position and intensity of PL emission peaks are similar when O2 flux is above the critical value, and the emission mechanism can be attributed to electron transitions mediated by defect levels in the bandgap, such as V O and F O. Just because of formation of SnO2 phase in the films and existence of relatively larger amount of V O and F O, the films show low resistivity and high transmittance at suitable O2 fluxes.

Doping of SnO2 with H atoms: An alternative way to attain n-type conductivity

We propose an explanation for the origin of n-type electrical conductivity in SnO2 based on the results obtained from the DFT+U simulations. Two competitive intrinsic point defects, namely oxygen vacancy and hydrogen impurity, have been considered at different positions within the crystalline lattice in order to find out the equilibrium configurations and to analyze corresponding density of states (DOS) patterns along with the electron localization function (ELF). It has been demonstrated that hydrogen could be solely responsible for the n-type conductivity whereas the oxygen vacancy appears to have not a notable influence upon it. The computational analysis is backed up by some experimental data for undoped tin dioxide.

Optical Generation and Transport of Charges in Iron Pyrite Nanocrystal Films and Subsequent Injection into SnO2

The low photovoltaic efficiency of iron pyrite-based solar cells is often related to the presence of sulfur deficiencies. In this paper surfur-rich iron pyrite nanocrystals (FeS2 NCs) are synthesized by the hot injection method and deposited using layer by layer deposition. Optical absorption measurements show substantial sub-bandgap absorption, which is attributed to a sulfur-rich, thin surface layer. Microwave photoconductance measurements show very little signal of films with the original long ligands, while an approximately 100-fold higher signal is observed for films treated with FeCl2 and 1,2-ethanedithiol (EDT) solutions. In mesoporous hybrid systems of FeS2/SnO2 both sub-band-gap and above-band-gap photons lead to electron injection from FeS2 into the SnO2 conduction band. We explain these findings by proposing that pinning of the Fermi level by the surface layer leads to a downward band bending in the direction of the surface within the FeS2 NC. Hence, photoexcited electrons will first move toward the shell where they relax into empty surface states. As the holes remain behind in the core of the nanocrystals, this results in a charge-separated state with a long lifetime. Interestingly, these surface electrons are able to migrate in the FeS2 NP layer by interparticle tunneling and can still decay by injection into SnO2. Hence, our results indicate that SnO2 is a suitable electron acceptor for FeS2. The long-lived charge-separated electrons and holes could be exploited efficiently in photodetectors.

Temperature dependent electron transport properties of degenerate SnO2 thin films

The degenerate SnO2 thin films were deposited on n-type Si substrates by using the magnetron sputtering system. The conductivity and Hall effect measurements of the films were carried out as a function of temperature. The measured temperature dependent conductivity of SnO2 has been analyzed using a comprehensive conductivity model including both the electron-electron scattering and the weak localizations effects. The characteristic parameters describing the conductivity such as the electron-electron scattering coefficient and the weak localization coefficient were determined both experimentally and theoretically, and their values were also discussed within the model describing the conductivity in degenerate SnO2 films with n > 1019 cm−3.

SnO2-Supported Electrocatalysts on Conductive Fillers for PEFCs

Introduction Electrocatalyst layer of polymer electrolytefuel cells (PEFCs) has complex 3-dimensional structure, and therefore control and optimization of microstructure is necessary for higher I-V performance. Carbon black supported cathode catalyst is generally used, however carbon supports can be degraded through oxidation on the cathode side. Thus, SnO2 support which is conductive and stable under the strongly-acidic cathode condition could be alternative support materials [1-3]. The objective of this study is thus to develop MEAs with higher performance and durability using SnO2 supports on conductive fillers for optimizing microstructural design of electrocatalysts. Experimental Sn0.98Nb0.02O2 was synthesized via the ammonia co-precipitation method or the homogeneous precipitation method. Pt nanoparticles were decorated on such a metal oxide support by using platinum acetylacetonate complex as a precursor. Microstructure of MEAs was modified by changing Nafion-to-electrocatalyst ratio (hereafter, Nafion ratio) systematically. The performance of MEAs was evaluated by measuring I-V characteristics and separating each overvoltage. Two series of MEAs were prepared and evaluated: MEAs with different conductive fillers (VGCF and CNT) and MEAs with different SnO2loadings on the conductive fillers. Results and Discussion I-V performance with different Nafion ratios is shown in Fig. 1. MEA with Pt/SnO2(Nb)/VGCF + 23wt. % Nafion exhibited the highest I-V performance in this study. In case Nafion ratio decreased from 23wt. %, I-V performance was degraded. However, the differences of each I-V performance were small. When Nafion ratio increased from 23wt. %, I-V performance decreased notably mainly due to higher concentration overvoltage. This is because open pores as gas transport pathway were filled with Nafion ionomer. I-V performance with different conductive fillers and different SnO2 loadings are shown in Fig. 2. I-V performance of MEA with CNT as the conductive filler was comparable to that of MEA with VGCF as the conductive filler. In case SnO2 loading increased, I-V performance was improved. This is attributed to better dispersion of Pt nano-particles. In case CNT was used as the conductive filler, the distribution of SnO2 particles on CNTs was often inhomogeneous so that Pt nano-particles were aggregated. Accordingly, surface area of Pt was reduced and activation overvoltage became higher. When SnO2 loading was increased, surface area of SnO2 was increased too and Pt nano-particles were highly dispersed, leading to lower activation overvoltage. In this study, cell voltage of the MEA with Pt/SnO2(Nb)/VGCF (SnO2 loading: 50wt. %) and MEA with Pt/SnO2(Nb)/CNT (SnO2 loading: 70wt. %) was 95% of that of MEA with 46.4wt. % Pt/KB at 0.2 A/cm2. High I-V performance of MEAs with SnO2support on conductive fillers is thus confirmed. Reference [1]K. Kanda, Z. Noda, Y. Nagamatsu et al., ECS Electrochem. Lett., 3(4) F15-F18 (2014) [2]T. Tsukatsune, Y. Takabatake, Z. Noda et al., J.Electrochem.Soc., 161(12) F1208-F1213 (2014) [3]F. Takasaki, S. Matsuie, Y. Takabatake et al., J.Electrochem.Soc., 158(10) B1270-B1275 (2011) Figure 1

Cascading Alignment of Multilayered SnO2/WO3/BiVO4 Inverse Opal Skeletons in Photoelectrochemical Water Splitting

Tin dioxide (SnO2) inverse opals (IOs) having a pore size of approximately 260 nm in the 370 nm sized polystyrene bead (PS) templates were developed by a spin-coating-assisted sol−gel process. Upon this template, the SnO2/WO3 core-shell IOs were developed by the facile electrodeposition under a constant potential (−0.47 V vs. sat. Ag/AgCl), where the thickness of WO3 layer depended on the applied charge amount for WO3 electrodeposition (200−800 mC/cm2). As a control sample, a pure WO3 IO film with the same thickness of ∼3.1 μm and a band gap (Eg ) of 2.6 eV was also prepared in the same method. The pore diameter of the SnO2 IO structure declined noticeably as the charge amount of the deposited WO3 layer increased from 200 to 800 mC/cm2, leading to eventual coverage of the SnO2 IO structure in the WO3 (800 mC/cm2) layer. The optimum photoelectrochemical (PEC) response was achieved with the SnO2/WO3 (600 mC/cm2) IO electrode, which exhibited the highest photocurrent density (Jsc) of 2.8 mA/cm2 (0.5 VAg/AgCl) under full-sun conditions and 0.91 mA/cm2 (0.5 VAg/AgCl) under visible light, indicating that the enhancement of the Jsc under visible light contributed significantly to the improvement of the total Jsc, compared with the values for the pure SnO2, SnO2/WO3 (200, 400, and 800 mC/cm2), and WO3 IO electrodes. Furthermore, considering that the favorable cascading band alignment can boost the fast charge separation and transport through the conductive SnO2 IO skeleton, we try to develop the multilayered SnO2/WO3/BiVO4 IOs structure showing the well-matched band alignment. And then, the dual doped (W and Mo) BiVO4 layer was adapted in the surface layer due to the more narrowing Eg of ~ 2.4 eV. Herein, the PEC performance and other results would be presented. Figure 1

Oxygen-controlled structures and properties of transparent conductive SnO2:F films

The morphology and properties of the transparent SnO2:F (FTO) films, deposited by RF magnetron sputtering at varying oxygen flows from 0∼3sccm, were examined. For FTO films deposited with 0∼1sccm O2, the polar unsaturated (101) planes were the preferred orientation, resulting in resistivity values as low as 10−3 Ω cm, and the transparency of 86.5% in the visible range. The saturated (110) orientation planes associated with {101} facets formed knee twin crystallites for the FTO film prepared at 2sccm O2. Further increases of O2 led to severe mis-orientation of the crystals. The average transparency in the visible range increased up to 95%, but these FTO films were hardly conductive due to the oversupply of O2. The optical band gaps became wide at first and then narrow again as the increases of the oxygen flow rates.

Structural, photoconductive, thermoelectric and activation energy measurements of V-doped transparent conductive SnO2 films fabricated by spray pyrolysis technique

This report investigated the structural, optical and electrical properties of V-doped SnO2 thin films deposited using spray pyrolysis technique. The SnO2:V films, with different V-content, were deposited on glass substrates at a substrate temperature of 550°C using an aqueous ethanol solution consisting of tin and vanadium chloride. X-ray diffraction studies showed that the SnO2:V films were polycrystalline only with tin oxide phases and the preferred orientations are along (1 1 0), (1 0 1), (2 1 1) and (3 0 1) planes. Using Scherrer formula, the grain sizes were estimated to be within the range of 25–36 nm. The variation in sheet resistance and optical direct band gap are functions of vanadium doping concentration. Field emission scanning electron microscopy (FESEM) revealed the surface morphology to be very smooth, yet grainy in nature. Optical transmittance spectra of the films showed high transparency of about ∼69–90% in the visible region, decreasing with increase in V-doping. The direct band gap for undoped SnO2 films was found to be 3.53 eV, while for higher V-doped films it shifted toward lower energies in the range of 3.27–3.53 eV and then increased again to 3.5 eV. The Hall effect and Seebeck studies revealed that the films exhibit n-type conductivity. The thermal activation energy, Seebeck coefficient and maximum of photosensitivity in the films were found to be in the range of 0.02–0.82 eV (in the low-temperature range), 0.15–0.18 mV K−1 (at T = 350 K) and 0.96–2.84, respectively.

Study of charge transport in Fe-doped SnO2 nanoparticles prepared by hydrothermal method

In order to follow the electrical comportment of the tin oxide (SnO2) with iron (Fe) addition, Fe doped SnO2 nanoparticles with various iron contents (0, 5%, 10%, 15% and 20 at%) were prepared via hydrothermal method. The effect of introducing iron in the structural, optical and electrical properties of SnO2 has been studied. The X-ray diffraction (XRD) patterns show that the peaks are indexed to the cassiterite structure without any trace of an extra phase even for relatively high Fe doping (20%). The impedance spectra were analyzed in terms of equivalent circuits involving resistors and constant phase elements (CPE). From the impedance measurements, the ac conductivity σac(ω) was calculated and studied. The electrical resistivity shows an increase with iron ratio. A conversion from n- to p- conductivity type with iron incorporation was interpreted. In SnO2 nanostructures, the surface activity and the grain size seem to be a major factors that must to be taking into account when looking for the modification of the material conductivity through doping. In fact, and contrary to what has been expected, the activation energy was found to increase with iron concentration. This rise was attributed to the expansion of the grain boundaries role in conductivity process and confirms the highly sensitive character of Fe-doped SnO2 surface. This fact was confirmed by the calculation of the Schottky barrier. The optical diffuse-reflectance measurement was carried out and a large reduction of the band gap was observed with iron ratio showing that a band gap decrease do not necessarily signify an amelioration of SnO2 conductivity.

Post Thermal Oxidation of Tin Thin Film on Silicon Substrate for MIS Hetrojunction Prepared by Thermal Evaporation

In this work, preparation of high quality conductive oxide SnO2 thin film by post-thermal trearment of deposited tin by vacuum thermal evaporation on glass and p -type silicon substratesfor preparation of metal-insulator-semiconductor hetrojunction. The opticalabsorption, electrical, structural and surface morphology of the SnO2 thin film on glass substrate were characterized byUV-VIS-NIR spectrophotometer, electrical conductivity, X-ray diffraction spectrum andatomic force microscope respectively. The X-Ray Diffraction pattern show that the SnO2 thin film is polycrystalline with and tetragonal rutile, Atomic Force Microscope show that the grains size of the thin film varies from 50 to 150 nm .The optical properties show that SnO2 thin film is high absorbance in Ultra-violet region, whereas it's transparent in the visible and near infrared regions and have direct optical band gap of 3.6 eV, and last the electrical conductivity results show that the resistivity is decrease with increase the temperature and activation energy is approximately to the 0.107eV. The electrical properties of n SnO2/SiO2/p Sihetrojunctionwere studied by I–V measurement under dark and illumination conditions, in the dark condition, I–V measurement reveals that the heterojunction have rectifying behavior, the ideality factor and the reverse saturation current of this diode are 5.18 and 1.5×10–6 A respectively. Under illumination condition, I–V measurement reveals that the photocurrent is larger than the dark current, and a linear relation between ISC and VOC with the incident light intensity to reach a maximum value beyond tends to saturated and become constant. These electrical properties of prepared device can its work as a detector or solar cell.

Resistive switching effect in metal–oxide–metal structures with ZnO:Li oxide layer

The resistive switching effect in metal–oxide–metal (MOM) structures has been investigated, where the 10% Li-doped ZnO layer was used as an oxide layer, as well as Pt and 20% fluorine doped SnO2 (SnO2:F) were used as a bottom electrodes. The current–voltage (I–V) and switching (I–t) characteristics of Ag/ZnO:Li/Pt and Ag/ZnO:Li/SnO2:F structures were investigated. The unipolar resistive switching is detected in the structures with the Pt, while the use of transparent conductive SnO2:F electrode instead of Pt, results to the bipolar memory effect.