Optimization of Gas Sensing Performance of Nanocrystalline SnO_2 Thin Films Synthesized by Magnetron Sputtering

Tin oxide （SnO2） is one of the most promising transparent conducting oxide materials, which is widely used in thin film gas sensors. We investigate the dependence of the deposition time on structural, morphologicaJ and hydrogen gas sensing properties of SnO2 thin films synthesized by dc magnetron sputtering. The deposited samples are characterized by XRD, SEM, AFM, surface area measurements and surface profiler. Also the H2 gas sensing properties of SnO2 deposited samples are performed against a wide range of operating temperature. The XRD analysis demonstrates that the degree of crystallinity of the deposited SnO2 films strongly depends on the deposition time. SEM and AFM analyses reveal that the size of nanoparticles or agglomerates, and both average and rms surface roughness is enhanced with the increasing deposition time. Also gas sensors based on these SnO2 nanolayers show an acceptable response to hydrogen at various operating temperatures.

Optoelectronic properties of SnO2 thin films sprayed at different deposition times

This article presents the elaboration of tin oxide （SnO2） thin films on glass substrates by using a home-made spray pyrolysis system. Effects of film thickness on the structural, optical, and electrical film properties are investigated. The films are characterized by several techniques such as x-ray diffraction （XRD）, atomic force microscopy （AFM）, ultraviolet- visible （UV-Vis） transmission, and four-probe point measurements, and the results suggest that the prepared films are uniform and well adherent to the substrates. X-ray diffraction （XRD） patterns show that SnO2 film is of polycrystal with cassiterite tetragonal crystal structure and a preferential orientation along the （110） plane. The calculated grain sizes are in a range from 32.93 nm to 56.88 nm. Optical transmittance spectra of the films show that their high transparency average transmittances are greater than 65% in the visible region. The optical gaps of SnO2 thin films are found to be in a range of 3.64 eV-3.94 eV. Figures of merit for SnO2 thin films reveal that their maximum value is about 1.15 x 10-4 Ω-1 at λ = 550 nm. Moreover, the measured electrical resistivity at room temperature is on the order of 10^-2 Ω.cm.

Electrodeposition of SnO_2 nanocrystalline thin film using butyl-rhodamine B as a structure-directing agent

Porous SnO2 nanocrystalline thin films were successfully electrodeposited from an oxygen-saturated acid aqueous solution of SnCl2 containing different concentrations of butyl-rhodamine B（BRhB） at 70℃.BRhB with substitute of amidocyanogen can be dissolved in the acid deposition solution,where HCl was added to suppress hydrolysis of SnCl2.So it was used as a structure-directing agent to promote the crystal growth of SnO_2.The formed porous morphology and tetragonal rutile crystalline structure of the electrodeposited thin films were controlled by the addition of BRhB with different amounts.

High Sensitivity of Porous Cu-Doped SnO2 Thin Films to Methanol

Porous Cu-doped SnO2 thin films were synthesized by the sol-gel dip-coating method for enhancing methanol sensing performance. The effect of Cu doping concentration on the SnO2 sensibility was investigated. XRD data confirm that the fabricated SnO2 films are polycrystalline with tetragonal rutile crystal structure. AFM and SEM micrographs confirmed the roughness and the porosity of SnO2 surface, respectively. UV-Vis spectrum shows that SnO2 thin films exhibit high transmittance in the visible region ~95%. The band gap (3.80 - 3.92 eV) and the optical thickness (893 - 131 nm) of prepared films were calculated from transmittance data. The sensing results demonstrate that SnO2 films have a high sensitivity and a fast response to methanol. In particular, 3% Cu-SnO2 films have a higher sensitivity (98%), faster response (10-2 s) and shorter recovery time (18 s) than other films.

Comparative Study of Structural, Optical and Electrical Properties of SnO₂Thin Film Growth via CBD, Drop-Cast and Dip-Coating Methods

Tin oxide (SnO2) thin films were deposited on glass substrate by Chemical Bath Deposition (CBD), Drop-Cast and Dip-Coating method. The thin films were post-annealed at 500°C for 2 hours. The structural, optical, and electrical properties of the SnO2 thin films were investigated by using XRD, FTIR, SEM, EDX, UV-Vis spectroscopy, and Electrometer experiment. The XRD patterns of SnO2 thin films deposited on glass substrate by CBD method, Drop-Cast method and Dip-Coating method showed cubic, tetragonal and amorphous structures respectively. The FTIR spectrum exhibited the strong presence of SnO2 with the characteristic vibrational mode of Sn-O-Sn. The SEM analysis was observed that the surface morphology of the thin films toughly depends on the deposition methods of the SnO2 thin films. EDX measurement confirmed that the thin films are the composition of Tin (Sn) and Oxygen (O2). The optical band gap of SnO2 thin films deposited by CBD method, Drop-Cast method and Dip-Coating method is found to be 3.12 eV, 3.14 eV and 3.16 eV respectively. Thin films deposited by Dip-Coating method showed the highest band gap. The electrical results confirmed that the SnO2 thin films are good conductors and pursued Ohm’s Law. These properties of the SnO2 thin films brand are appropriate for application in solar cell assembly, gas sensor devices and transparent electrodes of panel displays.

Preparation and Characterization of CeO_2-TiO_2/SnO_2:Sb Films Deposited on Glass Substrates by R.F.Sputtering

CeO2-TiO2 films and CeO2-TiO/SnO2：Sb （6 mol%） double films were deposited on glass substrates by radio-frequency magnetron sputtering （R.F. Sputtering）, using SnO2：Sb（6 mol%） target, and CeO2- TiO2 targets with different molar ratio of CeO2 to TiO2 （CeO2：TiO2-0：1.0; 0.1：0.9; 0.2：0.8; 0.3：0.7; 0.4：0.6; 0.5：0.5; 0.6：0.4; 0.7：0.3; 0.8：0.2; 0.9：0.1; 1.0：0）. The films are characterized by UV-visible transmission and infrared reflection spectra, scanning electron microscopy （SEM）, Raman spectroscopy, X-ray photoelectron spectroscopy （XPS） and X-ray diffraction （XRD）, respectively. The obtained results show that the amorphous phases composed of CeO2-TiO2 play an important role in absorbing UV, there are Ce^3-, Ce^4- and Ti^4- on the surface of the films; the glass substrates coated with CeO2-TiO2 （Ce/Ti=0.5：0.5; 0.6：0.4）/SnO2：Sb（6 mol%） double films show high absorbing UV（〉99）, high visible light transmission （75%） and good infrared reflection （〉70%）. The sheet resistance of the films is 30-50 Ω/□. The glass substrates coated with the double functional films can be used as window glass of buildings, automobile and so on.

Conduction Properties and Scattering Mechanisms in F-doped Textured Transparent Conducting SnO_2 Films Deposited by APCVD

Transparent conducting F-doped texture SnO2 films with resistivity as low as 5× 10-4 Ω ·cm,with carrier concentrations between 3.5 × 1020 and 7× 1020 cm-3 and Hall mobilities from 15.7 to 20.1 cm2/(V/s) have been prepared by atmosphere pressure chemical vapour deposition (APCVD). These polycrystalline films possess a variable preferred orientation, the polycrystallite sizes and orientations vary with substrate temperature. The substrate temperature and fluorine flow rate dependence of conductivity, Hall mobility and carrier conentration fOr the resultingfilms have been obtained. The temperature dependence of the mobiity and carrier concentrationhave been measured over a temperature range 16～400 K. A systematically theoretical analysis on scattering mechanisms for the highly conductive SnO2 films has been given. Both theoretical analysis and experimental results indicate that for these degenerate, polycrystalline SnO2 ：F films in the low temperature range (below 100 K), ionized impurity scattering is main scattering mechanism. However, when the temperature is higher than 100 K, the lattice vibration scattering becomes dominant. The grain boundary scattering makes a small contribution to limit the mobility of the films.

F掺杂SnO_2透明导电薄膜微结构及性能研究

通过实验测量常压热分解CVD工艺制备的F掺杂SnO2薄膜的方块电阻、膜厚、形貌、微结构、中远红外反射率等性质,详细研究了基板温度对SnO2薄膜微结构的影响和微结构与薄膜电学、光学性能之间的关系。研究发现,将基板温度从375℃提高到525℃以上,薄膜结晶程度大大提高,薄膜厚度从25nm提高到近300nm,方块电阻下降了两个数量级,中远红外的反射率达到了85%以上。

SnO_2:F导电薄膜的制备方法和性能表征

采用喷雾热分解(Spray pyrolysis)方法,以NH_4F、SnCl_2·2H_2O为原料,对反应液配方进行了优化,在普通玻璃衬底上制备出了光电性能优良的掺F二氧化锡透明导电薄膜。采用X射线衍射仪(XRD)、扫描电镜(SEM)、紫外-可见分光光度计(UV/VIS)对薄膜的结构、形貌、光学、电学特征进行了表征和分析。结果表明:在衬底温度为500℃,NH_4F/SnCl_2·2H_2O的质量百分比为20%,喷涂时间为15s时掺F二氧化锡薄膜的方块电阻最低达到6.2Ω/□,可见光透射率为86.95%,且薄膜晶粒均匀,表面形貌平整致密。

低温制备透明SnO_2:F薄膜的光电性研究

Sn O2 :F透明导电薄膜是一种广泛用于显示技术和能量转换技术的重要材料。本文在超声喷雾热解成膜技术基础上 ,对沉积装置进行了改进 ,同时对反应液配方进行了优化 ,在较低温度制备出透明 Sn O2 :F导电薄膜。用 XRD、UV/Vis、SEM、原子力显微镜分析测试方法对沉积薄膜的结构、形貌和光学、电学性质进行了研究。结果表明 ,在 360°C沉积温度下制备的 Sn O2 :F薄膜 ,其方块电阻为 4.7Ω,( 2 0 0 )面择优取向明显 ,薄膜晶粒均匀 ,表面形貌有所改善 ,透明度有所提高。

SnO_2气敏薄膜在SnO_2/Fe_2O_3双层结构中成核及生长过程的模拟

用ＳＥＭ对ＳｎＯ２／Ｆｅ２Ｏ３样品的断面结构进行了观察研究，发现ＳｎＯ２是在Ｆｅ２Ｏ３柱状结构的间隙中开始生长的，据此提出了双层膜结构生长热力学模型，由模型推出的结论与实验结果吻合。计算结果表明，ＳｎＯ２在Ｆｅ２Ｏ３薄膜的间隙中生长速度很快，而后逐渐变慢，达到稳定沉积速率，在这种沉积速率下形成ＳｎＯ２的柱状结构。ＳｎＯ２膜的这种沉积方式使得Ｆｅ２Ｏ３与其接触面积很大，两者结合十分牢固。

F掺杂对SnO_2薄膜组成、结构与光学性能的影响

以氯化亚锡、无水乙醇为主要原料,氢氟酸、氟硅酸和氟化铵为掺杂剂,采用溶胶-凝胶法制备了不同F掺杂浓度的SnO2透明薄膜,考察了氢氟酸、氟硅酸和氟化铵三种不同掺杂源的分别加入对薄膜物相组成、光学透过率以及微观结构的影响。分析结果表明,F掺杂SnO2薄膜具有的是单一四方金红石相结构,且F的掺杂能抑制薄膜中SnO2晶粒的长大,三种掺杂源中,以0～14mol%氟硅酸掺杂的SnO2薄膜表观质量最佳,且可见光范围内的透过率在75～85%之间。

超声喷雾法制备SnO_2:F薄膜及其性能研究

用超声喷雾热解淀积技术制备了ＳｎＯ２Ｆ透明导电薄膜，其电阻率达４×１０－４Ωｃｍ，可见光透过率达９１％。研究了衬底温度、Ｆ／Ｓｎ比例对ＳｎＯ２Ｆ薄膜光电特性的影响。ＸＲＤ分析及ＳＥＭ观察表明，ＳｎＯ２Ｆ薄膜为多晶结构，平均粒径约５０ｎｍ。对超声雾化及淀积原理进行了分析，由于溶液的超声雾化微粒均匀性好，载气流量与溶液雾化微粒线度无关，使得超声雾化热解淀积工艺控制相对容易，热解反应类型大多为化学气相淀积，所制备薄膜的均匀性和重复性良好。

SnO_2∶Fe_2O_3混合薄膜的制备及其在丙酮蒸汽中的反射光谱

以ＳｎＣｌ４·５Ｈ２Ｏ，ＦｅＣｌ３·６Ｈ２Ｏ及无水乙醇为主要原料，采用溶胶凝胶法制备了ＳｎＯ２∶Ｆｅ２Ｏ３混合薄膜，测量并研究了其在可见光区附近的丙酮气敏反射光谱。

二甲基二氯化锡前驱体CVD制备SnO2∶F薄膜及其性能研究

采用二甲基二氯化锡(DMTC)为新前驱体,通过常压CVD法在硼硅玻璃基板上制备SnO_2∶F透明导电薄膜,研究了DMTC、TFA和H_2O的含量对薄膜结构及光电性能的影响,研究表明当F/Sn物质的量比为1∶1、H2O/Sn物质的量比为3∶2时,制备出可见光透过率84.17%、方块电阻9.2Ω/□且结晶性能良好的多晶SnO_2薄膜。通过与单丁基三氯化锡(MBTC)为前驱体所制备薄膜的性能进行比较,结果表明,两种前驱体所制备薄膜均具有四方金红石结构,利用DMTC不仅可以制备出与MBTC性能相近的薄膜,同时薄膜表面更加均匀。

水热法合成F掺杂SnO2/石墨烯复合材料及其光催化性能研究

采用水热合成法,合成得到F掺杂SnO2/石墨烯复合材料,采用SEM、EDX和XRD等手段对产物进行表征。在可见光的照射下,研究其对罗丹明6G(R6G)的光催化降解效果。结果表明,F掺杂SnO2/石墨烯复合材料可以在60min将10mg/LR6G溶液完全降解。

晶向对SnO2：F透明导电玻璃特性的影响

本文利用超声喷雾法制备了SnO2：F透明导电薄膜，SnCl4·5H2O与NH4F分别用作锡源与氟掺杂，玻璃衬底温度控制在360℃。X射线衍射仪、扫描电镜、紫外可见分光光度计与四探针仪分别用于表征样品的晶体结构、表面形貌、透光率与面电阻。研究结果表明：超声喷雾沉积的SnO2：F薄膜主要为四方晶系的多晶薄膜，并且随着沉积条件的改变，在（110）、（220）晶向出现不同程度的择优取向，其中在（200）晶向上择优取向生长的薄膜面电阻明显低于（110）晶向，最低可达到5Ω／□，所有样品透光率都较高，在450-1000nm范围内的平均透光率可达到80-90％。

SnO_2-Sb-F电热膜的制备及其在化学反应器中的应用

采用溶胶凝胶法的无机工艺路线,在普通陶瓷管上制备Sb、F共掺的SnO2薄膜,研究了薄膜表面电阻与掺杂量、浸涂次数以及薄膜的发热温度的关系.其表面电阻最低为8Ω/□,薄膜的发热温度可达600℃以上,将其作为ClO2反应管的面源加热介质,通过改变电热膜面积,形成温度梯度和浓度梯度的双梯度反应方式,大大提高了反应物的转化率.

超声热解法制备SnO2:F薄膜加热管及其性能研究

采用超声喷涂热解淀积方法将SnO2:F透明导电薄膜制备于耐高温的硼硅玻璃管内壁.XRD物相分析及SEM、STM形貌分析表明,SnO2:F薄膜为多晶结构,平均粒径50nm.分析了薄膜中F取代SnO2中O的形成过程和薄膜电导率增强的机理,解释了不同的工艺条件对薄膜的结构、光电特性的影响,确定了制备SnO2:F薄膜加热管的最佳工艺条件.该条件下制备的薄膜的电阻率达4×10-4Ω·cm,可见光透过率高于90%,功率密度平均可达35 W/cm2.

喷雾热解法制备SnO2：Sb＋F透明导电薄膜

采用溶胶-凝胶与喷雾热解相结合的方法，在大面积浮法玻璃基板上制备出了SnO2：Sb＋F透明导电薄膜，研究了F／Sn比例、基板温度与SnO2薄膜的结构、形貌、光电性能的关系。实验结果表明：在溶胶的Sn：Sb：F比例为1：0．04：0.5和基板温度550℃的条件下，制备的SnO2：Sb＋F薄膜具有最佳的导电性能及较高的透光率，薄膜方阻达25Ω／□，电阻率为7．5×10^-4Ω·cm，平均可见光透过率为77．4％，辐射率e=0．208，表现出了较好的低辐射性。