Optical and electrical properties of electrochemically deposited polyaniline-CeO2 hybrid nanocomposite film

This paper reports the optical and electrical properties of electrochemically deposited polyaniline (PANI)-cerium oxide (CeO2) hybrid nano-composite film onto indium-tin-oxide (ITO) glass substrate. UV–visible spectroscopy and I-V characteristic were performed to study the optical and electrical parameters of the electrochemically deposited film. The film exhibited a strong absorption below 400 nm (3.10 eV) with a well defined absorbance peak at around 285nm (4.35 eV). The estimated band gap of the CeO2 sample was 3.44 eV and this value is higher than bulk CeO2 powder (Eg = 3.19 eV) due to quantum confinement effect.     

染料增感聚苯胺半导体薄膜的光电性能

采用电化学方法,利用有机染料对聚苯胺进行有机染料增感,制备出不同增感性能的聚苯胺薄膜。采用红外吸收光谱对增感后的聚苯胺的结构和性能进行了表征,对其在紫外－ 可见光区的吸收特性进行了研究。结果表明,染料增感后的聚合物薄膜电导率分别为：直接耐晒蓝增感为０ ．１４２ Ｓ／ｃｍ ;直接耐晒翠蓝增感为１ ．０５０ Ｓ／ｃｍ ;直接耐晒黑增感为０ ．７９６ Ｓ／ｃｍ ; 四羧基酞菁增感为１ ．２２０ Ｓ／ｃｍ 。这些增感均可使聚苯胺在可见光谱范围内的光吸收增强,较大幅度地改善聚苯胺的光谱响应范围,并使得有机染料增感后的聚苯胺薄膜保持很高的电导率     

不同基底上银薄膜的光电学性质研究

用热蒸发的方法,分别在孔径约为200nm的多孔阳极氧化铝(AAO)模板和空白石英基片上室温沉积厚为25～200nm的Ag薄膜样品,研究膜厚对两种样品的微观结构和光电学性质的影响。微观结构利用X射线衍射仪(XRD)和扫描电镜(SEM)观测,光电学性质应用分光光度计及Van derPauw方法检测。结果表明,石英基片上Ag(QuartzAg)薄膜的结晶性能比AAO模板上Ag(AAO-Ag)薄膜的结晶性能好,当厚为200nm时,AAOAg薄膜形成纳米颗粒的叠层结构;AAOAg薄膜的全反射率和QuartzAg薄膜的反射率均遵循随膜厚增加而增加的规律。在同一厚度和同一波长条件下,AAOAg薄膜的光学反射率比QuartzAg薄膜小很多,当厚为109nm时,在可见光和红外光区域,QuartzAg薄膜的反射率超过95%,而AAOAg薄膜的全反射率为40%;QuartzAg薄膜在厚度为25nm时已导电,而AAOAg薄膜的厚度为37nm时才开始导电。对于同一厚度,AAOAg薄膜的方块电阻比QuartzAg薄膜的大,随着膜厚的增加,它们的差值从厚为37nm时的4.90Ω/口逐渐减小到厚为200nm时的0.37Ω/口。     

Optical and electrical properties of CdGeAs2

Large-grained ingots of CdGeAs₂ have been grown from near-stoichiometric melts. Resistivity and Hall coefficient (R_H) measurements were made on a large number of samples at 77 and 300 K and in some cases up to 450 K. Good fits to the log R_H vs 1/T plots are obtained by using a model that assumes three kinds of electronic levels within the energy gap: donors, shallow acceptors, and acceptors with an ionization energy of 0. 30 eV. The deep acceptors are probably native defects, since their concentration varies by nearly four orders of magnitude from ingot to ingot with little change in impurity concentration. Between the intrinsic absorption edge at about 2. 5 Μm and the two-phonon absorption band at 18 Μm, the optical absorption increases with increasing deep acceptor concentration. By using oriented single-crystal samples ∼ 1 cm on a side, conversion efficiencies as high as 27% have been achieved for second-harmonic generation with single-mode pulses from a CO₂ TEA laser.     

Photoelectric properties of Cu2ZnSnS4 thin films deposited by thermal evaporation

正Sn/Cu/ZnS precursor were deposited by evaporation on soda lime glass at room temperature,and then polycrystalline thin films of Cu_2ZnSnS_4(CZTS) were produced by sulfurizing the precursors in a sulfur atmosphere at a temperature of 550℃for 3 h.Fabricated CZTS thin films were characterized by X-ray diffraction,energy dispersive X-ray spectroscopy,ultraviolet-visible-near infrared spectrophotometry,the Hall effect system,and 3D optical microscopy.The experimental results show that,when the ratios of[Cu]/([Zn]+[Sn]) and[Zn]/[Sn]in the CZTS are 0.83 and 1.15,the CZTS thin films possess an absorption coefficient of larger than 4.0 x 10~4 cm~(-1) in the energy range 1.5-3.5 eV,and a direct band gap of about 1.47 eV.The carrier concentration,resistivity and mobility of the CZTS film are 6.98 x 10~(16) cm~(-3),6.96Ω-cm,and 12.9 cm~2/(V-s),respectively and the conduction type is p-type.Therefore,the CZTS thin films are suitable for absorption layers of solar cells.     

聚合物/石墨纳米复合材料及其电学特性研究进展

从热固性树脂/石墨、热塑性树脂/石墨、橡胶/石墨和导电聚合物/石墨等几个方面综述聚合物/石墨纳米复合材料的研究现状。详细介绍了聚合物/石墨纳米复合材料的逾渗特性、伏安特性和压阻特性。对聚合物/石墨纳米复合材料的发展进行了展望。     

Correlation between the structural, morphological, optical, and electrical properties of In2O3 thin films obtained by an ultrasonic spray CVD process

Indium oxide (In₂O₃) thin films are successfully deposited on glass substrate at different deposition times by an ultrasonic spray technique using Indium chloride as the precursor solution; the physical properties of these films are characterized by XRD, SEM, and UV-visible. XRD analysis showed that the films are polycrystalline in nature having a cubic crystal structure and symmetry space group Ia3 with a preferred grain orientation along the (222) plane when the deposition time changes from 4 to 10 min, but when the deposition time equals 13 min we found that the majority of grains preferred the (400) plane. The surface morphology of the In₂O₃ thin films revealed that the shape of grains changes with the change of the preferential growth orientation. The transmittance improvement of In₂O₃ films was closely related to the good crystalline quality of the films. The optical gap energy is found to increase from 3.46 to 3.79 eV with the increasing of deposition time from 4 to 13 min. The film thickness was varied between 395 and 725 nm. The film grown at 13 min is found to exhibit low resistivity (10^-2 Ω·cm), and relatively high transmittance (~ 93%).     

Polyaniline composite coatings with thermally stable electrical properties

Polyaniline (PANI) composite coatings were prepared by polymerising aniline (ANI) monomers, which were previously embedded in an insulator polymer matrix (PMMA, PVK or PS), in an atmosphere saturated with aqueous HCl–(NH₄)₂S₂O₈ solution. The optical spectra and electrical measurements of these coatings clearly show the formation of the emeraldine salt of PANI in the composite materials. Sheet resistance data as well as an SEM morphology study suggest a surface polymerisation of aniline in the PANI–PMMA and PANI–PS composite coatings, whereas a volumetric polymerisation of aniline is evident in the PANI–PVK samples. The low percolation threshold (p_c) values of these coatings suggest a fibre structure of the PANI phase inside the composite materials. The curves of current versus temperature show a higher electrical property stability of the PANI–PVK composite coatings than of a PANI single film. Copyright © 1999 John Wiley & Sons, Ltd.     

CeO2掺杂对BaTiO3基陶瓷电介质的影响

研究采用固相法在BaTiO3中掺杂不同含量的CeO2对体系介电性能及微观结构的影响,讨论了不同烧结温度下体系介电性能的变化。研究发现,当组成为Ba(Ce0.08Ti0.92)O3时,试样在1 490℃保温2 h中可获得性能优良的电容器介质材料。体系的相对介电系数可达5 300,介质损耗仅为2.42%,绝缘电阻率为1.39×107Ω.cm,居里温度向室温方向移动至45℃。与此同时,借助扫描电镜对烧结体进行了微观形貌分析。结果表明,CeO2掺杂使Ce4 部分取代Ti4 ,有效地增加了体系的相对介电系数,降低了介质损耗,并起到了良好的居里峰展宽及移峰效应。此外,CeO2掺杂亦可抑制晶粒的异常长大,得到较高致密度的烧结体。     

漂珠/钡铁氧体/聚苯胺复合材料的制备及吸波性能研究

以溶胶–凝胶自蔓延燃烧法与原位掺杂聚合法相结合的方式制备了漂珠/钡铁氧体/聚苯胺复合材料。利用扫描电镜(SEM)、X射线衍射仪(XRD)和傅立叶红外光谱仪(FTIR)等表征了材料的微观形貌、晶体结构及组成。采用矢量网络分析仪在2~18 GHz频段内测定了复合材料的电磁参数。结果表明:所制材料的介质损耗和磁损耗最大值分别为0.30和0.52;当样品吸波层厚度为3.0 mm时,在电磁波频率为7.1 GHz时样品的反射损耗峰值为–33.74dB,在–20 dB的吸收带宽为3.2 GHz。     

制备过程中对VO_2薄膜热致相变光电性能的控制

本文利用真空还原V2 O5的方法制备出优质对VO2 薄膜 ;研究了不同真空还原时间VO2 薄膜热致相变过程中光电性能的影响 ;利用XPS、XRD对薄膜的化学状态和结晶状态进行了研究。制备的薄膜高 /低温电阻变化最大达到三个数量级 ,90 0nm处的光学透过率在相变前后改变了 40 %左右 ,热致相变性能优良。讨论了不同的真空还原时间下VO2 薄膜热滞回线的宽度、相变温度点以及高低温光透射性能。最后给出了最佳真空还原时间。     

Optical and structural properties of sol-gel derived nanostructured CeO2 film

Sol-gel derived nanostructured CeO2 film was deposited on glass substrate using by dip-coating technique with annealing at 65℃.X-ray diffraction (XRD),scanning electron microscopy (SEM),Fourier transform infrared (FTIR),UV/vis and photoluminescence (PL) spectroscopy studies were employed to analyze the structural and optical properties of the sol-gel derived nanostructured CeO2 film.The average crystallite size was estimated from the XRD pattern using by Scherrer equation as about 3-4nm.An SEM micrograph shows that the film was porous in nature and crack free.The UV-visible absorption spectroscopic measurement results showed that the products had conspicuous quantum size effects.The absorption spectrum indicates that the sol-gel derived nanostructured CeO2 film has a direct bandgap of 3.23 eV and the photoluminescence spectra of the film show a strong band at 378 nm:it may have a promising application as an optoelectronic material.     

CeO_2掺杂引起SnO_2压敏电阻的晶粒尺寸效应

研究了掺CeO2对SnO2Co2O3Ta2O5压敏电阻器性能的影响。研究发现:随着x(CeO2)从0增加到1%,压敏电压从190 V/mm增加到205 V/mm,相对介电常数从3 317减小到2 243,晶粒平均尺寸从12.16 mm减小到6.23 mm,在晶界上的Ce4+阻碍了SnO2晶粒的生长。为了解释样品电学非线性性质的起源,笔者提出了SnO2Co2O3Ta2O5CeO2晶界缺陷势垒模型。同时,对该压敏电阻器进行了等效电路分析,试验测量与等效电路分析结果相符。     

用直流磁控溅射法制备的ＩＴＯ薄膜的光电性能研究

用直流磁控溅射法将ＩＴＯ薄膜制备在玻璃基片上以作为太阳电池的透明电极。通过改变溅射功率、基片温度和工作气压来研究它们对所沉积的ITO薄膜的透过率和电导率的影响。实验结果表明：当溅射功率从30W增加到90W时,薄膜的透过率和电阻率都将减小;当基片温度从25℃ 增加到 150℃时,透过率稍微有点增大但电阻率减小;当工作气压从0.4Pa 增大到2.0Pa时,透过率减小,但电阻率增大。因此,在溅射功率为30W、基片温度为150℃、工作气压为0.4Pa 时,ITO薄膜有比较好的光电性能,其电阻率小于10-4 Ω•cm ,在可见光波段的透过率大于80%,适合于作为太阳电池的透明电极。     

用热蒸发法制备的Cu2ZnSnS4 薄膜的光电性能

在室温下用真空热蒸发法在玻璃基片上制备Sn/Cu/ZnS 前躯体膜层,然后对其在550C 下在硫气氛中硫化3小时以制得Cu₂ZnSnS₄ (CZTS) 多晶薄膜。对该薄膜进行X射线衍射（XRD）、能量色散X射线光谱（EDX）、紫外可见近红外分光光度计、霍尔测量系统和3D光学显微镜等分析测试。实验结果表明,当[Cu]/([Zn] [Sn]) =0.83和[Zn]/[Sn] =1.15时,该CZTS薄膜在光子能量范围在1.5 - 3.5 eV 时其吸收系数大于4.010₄cm_-1 ,直接带隙为1.47 eV。其载流子浓度、电阻率和迁移率分别为7.9710₁₆ cm_-3, 6.06 Ω.cm, 12.9 cm₂/(V.s), 导电类型为p型。因此,所制备出的CZTS 薄膜适合作为太阳电池的吸收层材料。     

Photoelectric properties of ITO thin films deposited by DC magnetron sputtering

As anti-reflecting thin films and transparent electrodes of solar cells,indium tin oxide（ITO） thin films were prepared on glass substrates by DC magnetron sputtering process.The main sputtering conditions were sputtering power,substrate temperature and work pressure.The influence of the above sputtering conditions on the transmittance and conductivity of the deposited ITO films was investigated.The experimental results show that, the transmittance and the resistivity decrease as the sputtering power increases from 30 to 90 W.When the substrate temperature increases from 25 to 150℃,the transmittance increases slightly whereas the resistivity decreases.As the work pressure increases from 0.4 to 2.0 Pa,the transmittance decreases and the resistivity increases.When the sputtering power,substrate temperature and work pressure are 30 W,150℃,0.4 Pa respectively,the ITO thin films exhibit good electrical and optical properties,with resistivity below 10^-4Ω·cm and the transmittance in the visible wave band beyond 80%.Therefore,the ITO thin films are suitable as transparent electrodes of solar cells.     

Structural, optical and electrical properties of SnxSy thin films grown by spray ultrasonic

Tin sulfide(Sn_xS_y) thin films were prepared by a spray ultrasonic technique on glass substrate at 300℃. The influence of deposition time t=2, 4, 6, 8 and 10 min on different properties of thin films, such as(XRD), photoluminescence(PL) and(UV) spectroscopy visible spectrum and four-point were investigated. X-ray diffraction showed that thin films crystallized in SnS₂, SnS, and Sn₂S₃ phases, but the most prominent one is SnS₂. The results of the(UV) spectroscopy visible spectrum show that the film which was deposited at 4 min has a large transmittance of 60% in the visible region. The photoluminescence spectra exhibited the luminescent peaks in the visible region, which shows its potential application in photovoltaic devices. The electrical resistivity(ρ) values of Sn_xS_y films have changed from 8.1×10^-4 to 1.62Ω·cm with deposition time.     

金属有机物化学气相淀积法生长的Si掺杂GaN薄膜的应力，结构与电学特性研究

The stresses, structural and electrical properties of n-type Si-doped GaN films grown by metaiorganic chemical vapor deposition （MOCVD） are systemically studied. It is suggested that the main stress relaxation is induced by bending dislocations in low doping samples. But for higher doping samples, as the Si doping concentration increases, the in-plane stresses in the grown films are quickly relaxed due to the rapid increase of the edge dislocation densities. Hall effect measurements reveal that the carrier mobility first increases rapidly and then decreases with increasing Si doping concentration. This phenomenon is attributed to the interaction between various scattering process. It is suggested that the dominant scattering process is defect scattering for low doping samples and ionized impurity scattering for high doping samples.     

Stress, structural and electrical properties of Si-doped GaN film grown by MOCVD

The stresses, structural and electrical properties of n-type Si-doped GaN films grown by metalorganic chemical vapor deposition (MOCVD) are systemically studied. It is suggested that the main stress relaxation is induced by bending dislocations in low doping samples. But for higher doping samples, as the Si doping concentration increases, the in-plane stresses in the grown films are quickly relaxed due to the rapid increase of the edge dislocation densities. Hall effect measurements reveal that the carrier mobility first increases rapidly and then decreases with increasing Si doping concentration. This phenomenon is attributed to the interaction between various scattering process. It is suggested that the dominant scattering process is defect scattering for low doping samples and ionized impurity scattering for high doping samples.     

Effect of rhenium doping on various physical properties of single crystals of MoSe2

Effect of rhenium doping is examined in single crystals of MoSe₂ viz. MoRe_0.005Se_1.995, MoRe_0.001Se_1.999 and Mo_0.995Re_0.005Se₂, which is grown by using the direct vapor transport (DVT) technique. The grown crystals are structurally characterized by X-ray diffraction, by determining their lattice parameters a and c, and X-ray density. Also, the Hall effect and thermoelectric power (TEP) measurements show that the single crystals exhibit a p-type semiconducting nature. The direct and indirect band gap measurements are also undertaken on these semiconducting materials.