Electrical Properties Of SnO2 Films Research Articles

Defect recombination suppression and carrier extraction improvement for efficient CsPbBr3/SnO2 heterojunction photodetectors

Perovskite materials with excellent optical and electronic properties have huge potential in the research field of photodetectors. Constructing heterojunctions and promoting carrier transportation are significant for the development of perovskite-based optoelectronics devices with high performances. Herein, we demonstrated a CsPbBr3/SnO2 heterojunction photodetector and improved the device performances through post-annealing treatment of SnO2 film. The results indicated that the electrical properties of SnO2 films will make an important impact on carrier extraction, especially for type-II heterojunction. As the electrons transfer layer in CsPbBr3/SnO2 type-II heterojunction, defects related to oxygen vacancy should be the key factor to affect carrier concentration, induce carriers’ limitation and recombination rate. Under proper annealing temperature for SnO2 layer, the recombination rate can decrease to 1.37 × 1021 cm3 s and the spectral responsivity will be highly increased. This work can enhance the understanding on the photoresponse of perovskite photodetectors, and will be helpful for the further optimization and design of optoelectronic devices based on the perovskite heterojunction.

Modulating Chemical Interaction to Realize Bottom‐Up Defect Passivation for Efficient and Stable Perovskite Solar Cells

The defects of perovskite and SnO2layers, interfacial energy barrier, and high grain boundary density impede further development of perovskite solar cells. Herein, a bottom‐up versatile modification strategy, which is implemented via introducing Lewis base ligand molecules containing different numbers of carbonyls (urea, propanedioic acid, and barbituric acid [BA]) into SnO2colloidal solution, is reported. All modifiers exhibit positive but different defect passivation effects for both SnO2and perovskite layers. The defect passivation effect can be rationally modulated by tuning the number of carbonyls and is directly proportional to the number of carbonyls. The enlargement sequence of the grain size is the same as that of the defect passivation effect. Meanwhile, the interfacial energy barrier, charge accumulation, and hysteresis are mitigated after modification, which is principally attributed to improved energy band alignment, reduced interfacial defects, and improved electrical properties of SnO2films. The BA‐modified device achieves an impressive efficiency up to 23.35%, which is significantly higher than 21.59% of the reference device. In addition, the modified devices demonstrate enhanced moisture and thermal stabilities.

Structure, Morphology and Optical Properties of SnO2 Nanoparticle Synthesized via Ultrasonic Spray Pyrolysis Technique: Effect of CuO Doping Concentration

Tin oxide (SnO2) and doped with various concentrations of copper oxide (CuO) of (3, 5, and 7%) nanoparticles were synthesized via a simple, cost-effective, and nontoxic ultrasonic spray pyrolysis technique on glass substrates. Crystalline structure, surface morphology of the SnO2 pure and SnO2:CuO, films have been studied by Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscope (AEM) and X-Ray Diffraction (XRD). The effect of CuO doping on the electrical properties of SnO2 films was investigated using Hall effect measurments. The optical properties of the prepared films have been characterized by Ultraviolet-visible spectrophotometer. High distribution densily and good growth SnO2 and SnO2: CuO nanoparticles on the substrate with an average particles size ranged from 30 to 110 nm. The crystalling and grain size were changed according to the CuO doping ratio. There is a redshift within the UV-Vis spectra was observed with an increasing CuO ratio of (3, 5 and 7%)

Influence of thermal cycling on the optical and the electrical properties of atmospheric pressure chemical vapor deposited tin oxide films grown using water and methanol vapors as oxidizers

Tin oxide films were chemically vapor deposited at atmospheric pressure at temperatures near 400 °C using SnCl4 as metal precursor and water or methanol vapors as oxidizers. The optical and electrical properties of these films were studied with spectroscopic ellipsometry (SE) and resistivity measurements while morphology and structure by scanning electron microscopy (SEM) and x-ray diffraction (XRD) measurements. It was found that both kinds of samples exhibited granular morphology with grain sizes of 10 and 80-100 nm for water and methanol deposited samples respectively. The crystallographic orientation of grains was similar for both kinds of samples. SE and resistivity measurements were simultaneously performed on samples up to 400 °C in air and at two thermal cycles. Using the Tauc-Lorentz combined with the Drude physical models the refractive index (real and imaginary parts) and the Tauc gap of samples were extracted from the SE measurements. Films morphology proved to be the decisive factor that governs optical and electrical properties of SnO2 films. So, large gained methanol vapor deposited SnO2 films were more than 80% transparent within the visible and an order of magnitude more conductive (resistivity of the order of 9-10 mΩ.cm) than the water deposited small-grained ones. It was also found that thermal cycling causes slight atomic re-arrangements in films that are invisible in XRD and SEM measurements but which influence significantly their optical and electrical properties.

Effect of Oxygen Source on the Various Properties of SnO2 Thin Films Deposited by Plasma-Enhanced Atomic Layer Deposition

Herein, we performed a comparative study of plasma-enhanced atomic layer deposition (PEALD) of SnO2 films using Sn(dmamp)2 as the Sn source and either H2O plasma or O2 plasma as the oxygen source in a wide temperature range of 100–300 °C. Since the type of oxygen source employed in PEALD determines the growth behavior and resultant film properties, we investigated the growth feature of both SnO2 PEALD processes and the various chemical, structural, morphological, optical, and electrical properties of SnO2 films, depending on the oxygen source. SnO2 films from Sn(dmamp)2/H2O plasma (SH-SnO2) and Sn(dmamp)2/O2 plasma (SO-SnO2) showed self-limiting atomic layer deposition (ALD) growth behavior with growth rates of ~0.21 and 0.07–0.13 nm/cycle, respectively. SO-SnO2 films showed relatively larger grain structures than SH-SnO2 films at all temperatures. Interestingly, SH-SnO2 films grown at high temperatures of 250 and 300 °C presented porous rod-shaped surface morphology. SO-SnO2 films showed good electrical properties, such as high mobility up to 27 cm2 V−1·s−1 and high carrier concentration of ~1019 cm−3, whereas SH-SnO2 films exhibited poor Hall mobility of 0.3–1.4 cm2 V−1·s−1 and moderate carrier concentration of 1 × 1017–30 × 1017 cm−3. This may be attributed to the significant grain boundary and hydrogen impurity scattering.

Gadolinium doping effect on SnO2 thin films optical and electrical properties

Undoped SnO2 thin films, as well as Gd-doped SnO2 thin films, were deposited on glass substrate by spray pyrolysis technique. The effect of gadolinium concentration and substrate annealing on structural, optical and electrical properties of SnO2 films are investigated. The structural properties of these thin films were analyzed using x-ray diffraction (XRD). XRD analysis confirmed the polycrystalline tetragonal crystalline structure of the films with mainly (110) preferential growth plane. The crystallite size has been reduced from 35 nm to 15 nm with increasing Gd dopant concentration. The films optical transmittance spectra exhibit high transparency of about 76%–87% in visible region. The films optical gap is enlarged from 3.43 eV in the un-doped films to 3.71 eV when Gd doped. The films figure of merit revealed a maximum value of about 8.2 × 10–3(Ω/sq)−1 at 550 nm wavelengths. The highest conducting and transparency are obtained in the film prepared with 3 wt% Gd doping ratio. Hence, we conclude that 3 wt% ratio is the optimal one required for Gd:SnO2 film production that may found optoelectronic applications, in particular, as window layer in solar cells.

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.

STUDYING STRUCTURAL, OPTICAL, ELECTRICAL, AND SENSING PROPERTIES OF NANOCRYSTALLINE SnO2:Cu FILMS PREPARED BY SOL–GEL METHOD FOR CO GAS SENSOR APPLICATION AT LOW TEMPERATURE

Nanocrystalline SnO2 and SnO2:Cu thin films derived from SnCl[Formula: see text]H2O precursors have been prepared on glass substrates using sol–gel dip-coating technique. The deposited film was [Formula: see text][Formula: see text]nm thick and the films were annealed in air at 500[Formula: see text]C for 1[Formula: see text]h. Structural, optical and sensing properties of the films were studied under different preparation conditions, such as Cu-doping concentration of 2%, 4% and 6[Formula: see text]wt.%. X-ray diffraction studies show the polycrystalline nature with tetragonal rutile structure of SnO2 and Cu:SnO2 thin films. The films have highly preferred orientation along (110). The crystallite size of the prepared samples reduced with increasing Cu-doping concentrations and the addition of Cu as dopants changed the structural properties of the thin films. Surface morphology was determined through scanning electron microscopy and atomic force microscopy. Results show that the particle size decreased as doping concentration increased. The films have moderate optical transmission (up to 82.4% at 800[Formula: see text]nm), and the transmittance, absorption coefficient and energy gap at different Cu-doping concentration were measured and calculated. Results show that Cu-doping decreased the transmittance and energy gap whereas it increased the absorption coefficient. Two peaks were noted with Cu-doping concentration of 0–6[Formula: see text]wt.%; the first peak was positioned exactly at 320[Formula: see text]nm ultraviolet emission and the second was positioned at 430–480[Formula: see text]nm. Moreover, emission bands were noticed in the photoluminescence spectra of Cu:SnO2. The electrical properties of SnO2 films include DC electrical conductivity, showing that the films have two activation energies, namely, [Formula: see text] and [Formula: see text], which increase as Cu-doping concentration increases. Cudoped nanocrystalline SnO2 gas-sensing material has better sensitivity to CO gas compared with pure SnO2.

Influence of multilayer deposition on characteristics of nanocrystalline SnO2 thin films produce by sol-gel technique for gas sensor application

Nanocrystalline SnO2 thin films have been prepared on glass substrates using sol-gel dip-coating technique. The deposited films were annealed in air at 500°C for one hour. Structural, optical, electrical, and sensing properties of the films were studied for different number of layers. X-ray diffraction spectra reveal the polycrystalline nature of the SnO2 films with tetragonal crystal structure, and have preferred growth direction along (110). The crystallite size of the thin films increased with increasing number of layers. AFM and SEM results indicated that the average grain size increased as number of layers increased. The optical band gap energy and transmittance of dip-coated films decreased as number of layers increased. The electrical properties of SnO2 films include DC electrical conductivity, showing that the films have two activation energies, namely, Ea1 and Ea2, which increase as number of layers increases. The films were further investigated in terms of their sensing abilities for carbon monoxide (CO) and nitrogen dioxide (NO2) gases at 50ppm by measuring their sensitivity to these gases at different times and temperatures. Our results demonstrated that dip-coated prepared films were highly sensitive to CO and NO2 at 200°C.

Effect of Mg doping on optical and electrical properties of SnO2 thin films: An experiment and first-principles study

Transparent Mg-doped p-type conductive SnO2 thin films were fabricated on quartz substrates by sol–gel method. Effect of Mg doping on structural, morphological, optical, and electrical properties of SnO2 films were investigated. A single phase of tetragonal rutile structure was observed in Mg-doped SnO2 films. The optical bandgap energy of the Mg-doped SnO2 films showed a systematical redshift with respect to the undoped SnO2 film, and the resistivity significantly increased with the increase of Mg concentration. A conduction type transform from n to p was also observed. The strong ultraviolet and comparatively weak blue/green emissions were observed in room temperature photoluminescence, suggesting the dipole-forbidden rule of bulk SnO2 is broken in Mg-doped SnO2 films. These results were supported by first-principles electronic structure calculations.

Electrical And Microstructural Properties Of (Cu, Al, In)-doped SnO2 Films Deposited By Spray Pyrolysis

The effect of Cu, Al and In doping on the microstructural and the electrical properties of the SnO2 films were studied. The undoped, Cu, Al and In (2 at. %) doped SnO2 films were deposited on the glass substrate by spray pyrolysis from 0.8 M SnCl2– ethanol solution at substrate temperature 400 °C. The microstructural properties of films were investigated by X-ray diffraction (XRD) method. It was determined that the films formed at polycrystalline structure in tetragonal phase and structure was not changed by dopant species. The lattice parameters (a), (c) and crystallite size (D) were determined and obtained in the range of 4.90-4.92 A, 3.26-3.31 A and 34-167 A, respectively. The optical transmittance of thin films was measured and the optical band gap Eg values of the films were obtained in the range of 3.96-4.00 eV, using the Tauc relation. The electrical transport properties of undoped, Cu, Al and In-doped SnO2 films were investigated by means of conductivity measurements in a temperature range of 120-400 K. The electrical transport mechanism of the undoped, Cu, Al and In-doped SnO2 films was determined by means of the tunneling model through the back-to-back Schottky barrier and the thermionic field emission model in the temperature range of 120-300 K and 300-400 K, respectively. Copyright © 2014 VBRI press.

Effect of fluorine doping on the structural, optical and electrical properties of SnO2 thin films prepared by spray ultrasonic

The undoped and fluorine doped tin oxide (SnO2) thin films are synthesized by using cost-effective spray ultrasonic technique; the films are sprayed on heated glass substrates at 480°C. The dependence of structural, optical and electrical properties of SnO2 films on the concentration of fluorine is investigated. X-ray diffraction, Optical absorption, four-point probe and Hall Effect studies have been performed on undoped and fluorine doped SnO2 (FTO) films. X-ray diffraction pattern reveals the presence of cassiterite structure with (200) as preferential orientation for FTO films. The crystallite size varies from 10.3 to 27.12nm and was affected by F concentration which was lying between 0 and 12wt.%. All films exhibit optical transmission T(λ) more than 83.9% in visible region; the optically estimated film thickness varies from 700 to 975nm for the same given time (3min deposition) and band gap (Eg) varies from 3.651 to 3.902eV. The electrical study reveals that the films have n-type electrical conductivity and depend upon fluorine concentration too. The sprayed FTO film doped at 6wt.% has the minimum resistivity of 1.47×10−3Ωcm and minimum resistance sheet (Rsh) of 21Ω/cm2 whereas the carrier concentration and mobility were about 2.04×1019cm−3 and 208.4cm2V−1s−1 respectively.

Structural and electrical properties of SnO2 films grown on r-cut sapphire at different substrate temperature by MOCVD

Tin oxide (SnO2) films have been grown on r-cut sapphire substrates by metalorganic chemical vapor deposition (MOCVD). The substrate temperature dependent structural and electrical properties of SnO2 films were investigated. It was found that the films deposited at lower temperatures were polycrystalline while the highly oriented growth occurred above 600 °C. Especially, high-quality SnO2 film with no (101) twin structure was obtained at 700 °C. Scanning electron microscopy showed that the surface morphology was significantly affected by the substrate temperature. A tile-like surface was observed for the film grown at 700 °C. The change in electrical properties for the SnO2 films was associated with the various structures at different substrate temperatures.

A study on the graphene incorporated direct‐patternable SnO2 thin film

AbstractThe electrical property of direct‐patternable SnO2 thin film was improved by the incorporation of graphene. Graphene were incorporated into SnO2 photosensitive solution and the direct‐patternable film was prepared by photochemical solution deposition. The incorporation of graphene into SnO2 films slightly reduced the transmittance of the films due to light scattering by the incorporated graphene. In addition, with incorporation of graphene, the crystallinity of the SnO2 thin films was decreased slightly and the resistivity was improved due to an enhancement of mobility because of the π‐bond nature of surface on graphene. Direct‐patterning of graphene incorporated SnO2 thin films was performed without photoresist or etching process. These results suggest that a micropatterned system can be simply fabricated at a low cost and the electrical properties of SnO2 films can be improved by incorporating graphene.

A study of the incorporation of conducting materials into direct-patternable SnO2 thin films formed by photochemical metal-organic deposition

Ag nanoparticles and multi-wall carbon nanotubes (MWNTs) were incorporated into a SnO2 photosensitive precursor solution, and a direct-patternable film was prepared by photochemical metal-organic deposition. SnO2 film transmittance and crystallinity were slightly reduced by light absorption of Ag nanoparticles and light scattering by MWNTs. In the case of mixed incorporation of Ag nanoparticles and MWNTs, the sheet resistance of SnO2 hybrid films was decreased relative to incorporation of either single material. Direct-patterning of SnO2 hybrid films was performed without photoresist or dry etching. These results suggest that a micro-patterned system can be simply fabricated at a low cost, and the electrical properties of SnO2 films can be improved by incorporating Ag nanoparticles with MWNTs.

Optical and electrical properties of SnO2 films prepared by chemical vapour deposition

Transparent and conducting SnO2 films are prepared at 500°C on quartz substrates by chemical vapour deposition technique, involving oxidation of SnCl2. The effect of oxygen gas flow rate on the properties of SnO2 films is reported. Oxygen with a flow rate from 0·8–1·35 lmin−1 was used as both carrier and oxidizing gas. Electrical and optical properties are studied for 150 nm thick films. The films obtained have a resistivity between 1·72 × 10−3 and 4·95 × 10−3 ohm cm and the average transmission in the visible region ranges 86–90%. The performance of these films was checked and the maximum figure of merit value of 2·03 × 10−3 ohm−1 was obtained with the films deposited at the flow rate of 1·16 lmin−1.