SnO2:Fe2O3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.     

双层结构TiO2-WO3气敏薄膜特性的研究

用直流反应磁控溅射法制备了TiO2-WO3双层结构的气敏薄膜,进行了薄膜微结构和化学成分分析,研究了TiO2表面层对WO3气敏特性的影响。实验证明:当TiO2膜厚为30 nm时,WO3薄膜对NO2敏感特性得到改善,TiO2-WO3结构的薄膜对空气中较低浓度的NO2(体积分数为(1~3)×10-5)具有优异的敏感特性和响应特性。最适宜的工作温度为120℃,在一些气体(如CO、H2S、C2H5OH、H2)中对NO2的选择性也大大提高。     

Ni掺杂α-Fe_2O_3纳米材料的制备及气敏性能研究

采用水热法合成了Ni掺杂α-Fe2O3纳米材料,通过XRD、TEM等手段对产物的物相、形貌等进行了表征,并探讨了材料的气敏性能。结果表明:工作温度为300℃时,元件对50×10–6的H2S气体的灵敏度可达122.8,H2S气体对其他几种被测气体的选择性系数均在9以上,响应恢复时间分别为5s和14s。最后提出了Ni掺杂对α-Fe2O3气敏元件性能影响的机理。     

超细铁酸镉材料的制备及其气敏性能研究

以FeSO4·7H2O和CdCl2·2.5H2O为原料,采用化学共沉淀法制备了纳米尺寸CdFe2O4粉体。利用X射线衍射仪、透射电镜对粉体的形貌、结构进行了表征。研究表明,用化学共沉淀法制备的CdFe2O4结晶情况良好,分布均匀,平均粒径约为80 nm。以CdFe2O4纳米粉体为原料制备了厚膜气敏元件,在工作温度为400左右时,该元件对乙醇具有较高的灵敏度、好的稳定性和选择性。并对气敏机理给予了解释。     

掺Sm2O3的SnO2纳米粉体对C2H2气敏特性的研究

用化学沉淀法制备了SnO2纳米材料,利用XRD和SEM对合成产物进行了表征.采用旁热式结构制成了以SnO2为基体材料,掺杂Sm2O3的气体传感器.通过元件对C2H2气敏特性的测试表明:Sm2O3的掺杂可以明显地提高SnO2气敏材料对C2H2气体的灵敏度,当工作温度为180℃,C2H2浓度为1000ppm时,元件的灵敏度为64,响应恢复时间分别为3和20s.讨论了不同相对湿度对元件气敏特性的影响.     

掺Sm2O3的SnO2纳米粉体对C2H2气敏特性的研究

用化学沉淀法制备了SnO2纳米材料,利用XRD和SEM对合成产物进行了表征.采用旁热式结构制成了以SnO2为基体材料,掺杂Sm2O3的气体传感器.通过元件对C2H2气敏特性的测试表明:Sm2O3的掺杂可以明显地提高SnO2气敏材料对C2H2气体的灵敏度,当工作温度为180℃,C2H2浓度为1000ppm时,元件的灵敏度为64,响应恢复时间分别为3和20s.讨论了不同相对湿度对元件气敏特性的影响.     

锌掺杂量对In_2O_3电导和气敏性能的影响

用化学共沉淀和热处理法于pH11.5～12.5时,用(NH4)2CO3作沉淀剂,制备了Zn2+掺杂的In2O3微粉。研究了Zn2+掺杂量对In2O3气敏元件电导和气敏性能的影响。结果发现,ZnO与In2O3可形成有限固溶体In2-xZnxO3(0≤x≤0.10);In1.95Zn0.05O3气敏元件在223℃工作温度下,对浓度为4.5×10–7mol/L的C2H5OH的灵敏度高达174.4,且选择性也好。     

sol-gel法制备Yb_2O_3掺杂纳米SnO_2及气敏性能研究

以SnCl_4·5H_2O与柠檬酸为原料,采用sol-gel法制备了掺杂质量分数w(Yb_2O_3)为0~1.0%的Yb_2O_3-SnO_2纳米粉体。利用XRD、TEM等测试手段分析了粉体的微观结构,采用静态配气法测试了由所制粉体制成的气敏元件对NO_2、Cl_2、H_2、H_2S、乙醇、甲醛等气体的气敏性能。结果表明:用该法得到的粉体颗粒粒径小,且均匀;工作温度为100℃时,由掺杂w(Yb_2O_3)为0.4%的SnO_2粉体,在烧结温度600℃制得的气敏元件,对体积分数为30×10–6的NO_2的灵敏度最高可达18224,且该元件具有较好的响应–恢复特性,响应时间和恢复时间分别是20s和15s。     

复合钒钛酸干凝胶薄膜的湿敏特性研究

采用sol-gel法制备了复合钒钛酸干凝胶(H2V10Ti2O30-y·nH2O)薄膜,并对其湿敏特性进行了研究。结果表明:该薄膜为层状结构。用此薄膜制备的湿敏元件,在RH为11%～95%的范围内,感湿特性曲线线性好,其响应、恢复时间分别为5s和20s,湿滞为RH2%,感湿温度系数为RH0.45%/℃,并具有良好的稳定性。H2V10Ti2O30-y·nH2O干凝胶薄膜湿敏元件的灵敏度和湿滞均优于复合钒酸(H2V12O31-y·nH2O)干凝胶薄膜湿敏元件。     

复合钒钼酸干凝胶薄膜湿敏特性的影响因素

采用sol-gel法制备复合钒钼酸H2V12–xMoxO31±y·nH2O(0≤x≤4)干凝胶薄膜并研究了Mo含量、电极及温度等对其湿敏特性的影响。结果表明:当工作频率为1kHz,温度20℃,涂覆于金电极上的H2V10Mo2O31±y·nH2O(x=2)干凝胶薄膜在全湿度范围内具有线性好、灵敏度较高、响应快、湿滞小的特点,是一种很有前途的新型湿敏材料。     

Sb∶SnO2/SiO2纳米复合薄膜的光学及气敏特性

采用溶胶 凝胶 (sol gel)工艺制备了Sb∶SnO2 /SiO2 复合膜。通过原子力显微镜 (AFM )观察了薄膜样品的表面形貌 ,利用紫外 可见光谱 ,p 偏振光反射比角谱研究了复合薄膜的光学特性。结果表明 ,薄膜中的晶粒具有纳米尺寸 (～ 35nm)的大小 ,比表面积大 ,孔隙率高 ;薄膜的透光率高 ,可见光波段近 95 % ;其光学禁带宽度约 3 6 7eV。因此Sb∶SnO2 /SiO2 纳米复合膜可作为气敏薄膜的理想选择。通过对三种不同的气体C3 H8,C2 H5OH及NH3气敏特性的测试表明 ,Sb掺杂大大提高了SnO2 薄膜对C2 H5OH的灵敏度 ,纳米Sb∶SnO2 /SiO2 复合膜的气敏灵敏度高于纯SnO2 薄膜及Sb掺杂的SnO2 薄膜     

液相生长热氧化法制备SnO2气体敏感薄膜

在不同的热氧化温度下,用液相生长热氧化法(RGTO)制备了SnO2薄膜。探讨了热氧化温度对SnO2薄膜结构和成分的影响,并进一步研究了不同热氧化温度下制备的SnO2薄膜的气敏性能。测试结果表明:260℃工作温度下,600℃热氧化制备的SnO2薄膜气敏元件,对氢气的灵敏度最佳。在100～1 000 mg.kg–1的氢气浓度范围内,灵敏度由47递增至70。     

The electrical conductivity of polycrystalline SnO2(Cu) films and their sensitivity to hydrogen sulfide

The effect of doping with copper on the sensor properties and the electrical conductivity of polycrystalline SnO₂(Cu) films has been investigated. It has been found that at room temperature the residual conductivity is observed after the films are exposed to H₂S. This made it possible to determine the character of the low-temperature conductivity of the films for different degrees of saturation with hydrogen sulfide. A comparison of the obtained data with the results of layerwise elemental analysis suggested a model that explains the mechanism of the gas sensitivity of SnO₂(Cu) to hydrogen sulfide. In contrast to the mechanisms, which are associated with the work done by the surface and which are standard for gas sensors, in the present case the change in the conductivity is due to the chemical reaction of the electrically active copper with sulfur in the entire volume of the film. This reaction determines the selectivity and high sensitivity of SnO₂(Cu) to H₂S. Fiz. Tekh. Poluprovodn. 31, 400–404 (April 1997)     

Preparation of Surfactants Directed PANI/In2O3 Nanocomposite Thin Films and Its NH3-Sensing Properties

Polyaniline/indium oxide(PANI/In2O3)nanocomposite thin films have been prepared in water-dispersed medium with the presence of different surfactants by an in-situ self-assembly technique.A cationic surfactant TTAB(tetradecyltrimethylammonium bromide)and a non-ionic surfactant tween20(poly(ethylene oxide)(20)sorbitan monolaurate)are used as additives.The nauocomposites and thin films are characterized by Fourier transform infrared(FTIR),transmission electron microscopy(TEM),and scanning electron microscopy(SEM),respectively.The optical properties reveal the Interaction between PANI/In2O3nanocomposites and surfactants,and PANI/In2O3 thin films prepared in the presence of surfaetants exhibits the finer nanofiber than the surfactants free PANI/In2O3thin film.The ammonia(NH3)gas-sensing characteristic of PANI/In2O3 thin films and the effect of different surfactants on the gas-sensing property are studied.The results indicated that the film processed in the presence of TTAB has the highest gas sensitivity among all the prepared films.     

Sb掺杂SnO2/SiO2纳米光学气敏薄膜的制备及其性质

采用溶胶凝胶(sol-gel)工艺制备了Sb掺杂SnO2/SiO2复合膜。通过X射线衍射(XRD)、傅立叶变换红外谱(FT-IR)及原子力显微镜(AFM)表征了薄膜样品的物相结构与表面形貌,利用紫外-可见光谱研究了复合薄膜光学特性．利用p-偏振光双面反射法对薄膜的气敏特性进行了测试。实验结果表明,薄膜中的晶粒具有纳米尺寸(～35nm)的大小．比表面积大,孔隙率高;薄膜的透光率高,可见光波段近95％;纳米Sb：SnO2：SiO2复合膜的气敏灵敏度高于纯SnO2薄膜及Sb掺杂的SnO2薄膜。     

SiC薄膜的制备及其对气氛的响应研究

在CH4,H2,SiH4混合气体中用热丝化学气相沉积(HFCVD)法生长SiC薄膜。利用XRD、原子力显微镜(AFM)对SiC薄膜的表面形貌和晶体结构进行测试分析,结果表明,薄膜的确是SiC,其厚度为310nm。对该薄膜在较高温度(250℃)下进行气敏特性测试,发现其对乙醇、乙醚有较好的敏感特性。进一步研究表明,不同的薄膜制备工艺条件对薄膜的气敏特性有一定的影响,其中H2流量,掺杂(N2)浓度对薄膜气敏特性影响较大。     

ZnO薄膜紫外光敏特性及晶界势垒的研究

以二水合醋酸锌为原料,采用sol-gel法在石英衬底上制备了ZnO薄膜。用AFM观察表面形貌,通过测量真空条件下不同温度热处理后薄膜的I-V特性,拟合计算晶界势垒高度。研究了热处理温度对ZnO薄膜性能的影响。结果表明:经650℃热处理制备的ZnO薄膜样品具有较佳性能,结构均匀致密,粒径分布为20～32nm。在10V偏压和1.24×10–3W/cm2光强下,紫外光灵敏度为43.95;无光照条件下晶界势垒高度为0.079eV。紫外光照使晶界势垒高度下降为0.011eV,薄膜的紫外光灵敏度与势垒高度的相对变化密切相关。     

Synthesis of highly selective and sensitive Cu-doped ZnO thin film sensor for detection of H2S gas

Copper (Cu) doped zinc oxide (ZnO) thin films were successfully prepared by a simple sol-gel spin coating technique. The effect of Cu doping on the structural, morphology, compositional, microstructural, optical, electrical and H₂S gas sensing properties of the films were investigated by using XRD, FESEM, EDS, FTIR, XPS, Raman, HRTEM, and UV–vis techniques. XRD analysis shows that the films are nanocrystalline zinc oxide with the hexagonal wurtzite structure and FESEM result shows a porous structured morphology. The gas response of Cu-doped ZnO thin films was measured by the variation in the electrical resistance of the film, in the absence and presence of H₂S gas. The gas response in relation to operating temperature, Cu doping concentration, and the H₂S gas concentration has been systematically investigated. The maximum H₂S gas response was achieved for 3 at% Cu-doped ZnO thin film for 50 ppm gas concentration, at 250 °C operating temperature.     

Effect of SnCl2 and SnCl4 precursors on SnSx thin films prepared by ultrasonic spray pyrolysis

Thin films of SnS_x, semiconductors, have been successfully synthesized by ultrasonic spray pyrolysis technique, using two precursors namely:tin (Ⅱ) chloride and tin (IV) chloride, respectively. The solutions were prepared by the dilution of different Sn molarities of the two precursors separately. The precursor molarities were varied from 0.04 to 0.07 mol/L, whereas that of S was fixed at 0.1 mol/L. The present work focuses on the effect of the different precursor''s molarities on the nature and the properties of the prepared thin films in order to optimize the growth conditions. X-ray diffraction analysis reveals that the precursor''s molarities alter the grain size of the prepared films, which varied from 8 to 14 nm and from 12 to 16 nm, according to the used precursor. The films analysis by SEM, shows that the SnS₂ films are more dense and smooth than the SnS films. The composition of the elements is analysed with an EDX spectrometer, and the obtained result for M_sn D 0:07 mol/L indicates that the atomic ratio of Sn to S is 51.57:48.43 and 36：64 for films synthesized from the first and second precursors respectively. Electrical measurements show that the conductivity behavior depends on the used precursors and their molarities.     

Influence of bismuth on the optical properties of Ge2Sb2Te5 thin films

Chalcogenide alloys in the Ge-Sb-Te system are promising for application in phase-change memory devices. We investigated the influence of bismuth on the optical properties of Ge₂Sb₂Te₅ thin films and established that the bismuth doping in them allows the optical contrast of the thin films to be increased by about 30% at a wavelength of 400 nm. The experimental results are explained in an assumption on the impurity substitution of bismuth for antimony.