磁控溅射Cu薄膜的光电性能研究

利用磁控溅射技术,通过正交试验设计方法,在K9光学玻璃基底上制备了Cu薄膜,研究了溅射时间、基底温度和氩气流量对Cu薄膜光电性能的影响.研究表明:Cu薄膜的透射谱在紫外波段362 nm处有明显吸收峰,但在可见光波段吸收强度较弱,说明Cu膜在可见波段有较高的透光性;膜厚度增加则光学透射率降低.电阻率随膜厚的增大,大体上呈逐渐减小的趋势;1100 nm 为临界尺寸,Cu膜厚度<1100 nm时,电阻率值变化较快;Cu薄膜厚度>1100 nm时,电阻率变化缓慢至定值.当溅射时间为25 min、基底温度为300 ℃、氩气流量为6.9 sccm时所得样品在紫外-可见光区没有吸收,且导电性好.     

Preparation and characterization of ZrO2-SiO2 binary films for planar optical waveguides

ZrO₂-SiO₂ binary films for active optical waveguides were prepared by the sol-gel method with zirconium oxychloride and tetraethoxysilane as precursors. The main factors that influence the film thickness and refractive index have been found. The relationship between the film refractive index composition and heat treatment temperature has been determined. The continuous tuning of the thickness and refractive index of the thin films has also been achieved, which will open up new possibilities in the development of active optical waveguides.     

Optical and electrical properties of Tl-S glasses

The frequency and temperature dependence of ac conductivity and optical absorption have been measured for four Tl-S glasses, TlS, Tl₂S₃,TlS₂ and Tl₂S₅, prepared by a melt-quenching method. The ac conductivity has been measured over a frequency range 0.1 Hz to 1.8 GHz and a temperature range 190-273 K. The optical absorption was measured at room temperature over a wavelength range 200-2600 nm. We have determined the electrical and optical band gaps from the experimental results. For each glass, the electrical band gap is larger than the optical band gap and the difference increases with increasing sulfur concentration. The frequency dependence of ac conductivity varies with composition of the glasses. We suggest that these results are due to an increase of localized states in the band gap with increasing sulfur concentration.     

碳电极钙钛矿太阳能电池光吸收层厚度对光伏性能的影响研究

本文使用两步法,通过控制PbI₂(DMSO)溶液的浓度制备了不同厚度的有机-无机杂化钙钛矿(MAPbI₃)光吸收层薄膜,并组装了大面积基于碳电极且无空穴传输层的钙钛矿太阳能电池。对不同厚度MAPbI₃光吸收层薄膜的晶相、光吸收性质、表面形貌、元素组成进行分析,并进一步测试了基于MAPbI₃薄膜制备的钙钛矿太阳能电池的光伏性能。结果表明,MAPbI₃光吸收层薄膜厚度与PbI₂(DMSO)浓度呈正相关关系,浓度为1.3 mol/L的PbI₂溶液制备的MAPbI₃薄膜厚度约为350 nm,具有较好的结晶度和光吸收强度,且薄膜表面致密平整,无明显缺陷,基于350 nm MAPbI₃光吸收层的钙钛矿太阳能电池获得了8.48%的光电转换效率。     

Effect of substrate temperature on the optical constants of zincphthalocyanine thin films

The influence of the film thickness and substrate temperature on optical constants of the vacuum evaporated ZincPhthalocyanine (ZnPc) thin films have been reported in this paper. The direct and allowed optical band gap energy has been evaluated from the (αhυ)² vs. (hυ) plots. The optical constants such as extinction coefficient (k_f) and refractive index (n) have been evaluated from the transmittance values and the observed results strongly dependent on substrate temperature and film thickness. The low values of the refractive index have been observed for the films prepared at T_s=200°C. The change in crystallanity and phase transformation affect the optical constants and the lower values of the optical constants will leads to the good quality of the ZnPc thin films. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical and structural properties of new chalcohalide glasses

New class of chalcohalide glasses has been prepared in the GeS₂–In₂S₃–CsI system with regard to their potential non-linear properties. The study of glass-forming region was undertaken to select glassy compositions, which present high non-linear (NL) optical properties with a low two-photon absorption. Thermal analyses, structural examination by Raman spectroscopy, non-linear optical measurements were investigated as a function of CsI contents. Introduction of CsI has shifted the band-gap edge towards the blue region of the absorption optical spectrum and therefore has limited the two-photon absorption. Their NL refractive index n₂ are 60 times higher than silica glasses without any NL absorption. Moreover, second harmonic signal was observed in thermally poled samples similar to silica glass. However, this second order non-linearity is not temporally stable.     

Synthesis and optical properties of poly[4-methacryloxy-(4′-carboxy)-azobenzene]

Abstract

In the present work, the homopolymer built from the free radical polymerization of methacrylic monomer incorporating an azobenzene side-group has been synthesized and structurally characterized. The optical properties such as refractive index, extinction coefficient, absorption coefficient and optical energy band gap of poly[4-methacryloxy-(4′-carboxy)-azobenzene] thin film prepared by high vacuum sublimation method were determined using spectroscopic ellipsometry combined with transmittance measurements.

We found that in the spectrum of extinction coefficient there are absorption bands, which are assigned as the n-π* and π-π* electronic transitions of the azo compound.     

Dielectric properties of bis(2,4 pentanedionato)copper(II) crystalline films grown on Si substrate for low-k applications

Bis(acetylacetonato)copper(II) thin films were prepared by sublimation at about 245 °C in vacuum on p-Si and glass substrates for dielectric and optical investigations. They were characterized by the X-ray diffraction (XRD) and energy-dispersion X-ray fluorescence (EDXRF) methods. The XRD pattern reveals that the prepared films were polycrystalline of monoclinic P2₁/n structure. The optical absorption spectrum of the prepared film was not identical to that of the molecular one, which identified by a strong absorption peak at 635 nm. The onset energy of the optical absorption of the complex was calculated by using Hamberg et al. method, which is usually used for common solid-state semiconductors and insulators. The dielectric properties for the complex as insulator were investigated on samples made in form of a metal-insulator-semiconductor (MIS) structure. The dielectric properties were studied in frequency range 1–1000 kHz and temperature range 298–333 K. The dielectric relaxation was analyzed in-terms of dielectric modulus M¹(ω). Generally, the present study shows that films of the complex grown on Si substrate are a promising candidate for low-k dielectric applications; it displays low-k value around 1.7 ± 0.1 at high frequencies.     

Optical band gap of zinc nitride films prepared by reactive rf magnetron sputtering

Polycrystalline Zn₃N₂ films are prepared on Si and quartz glass substrates by RF magnetron sputtering at room temperature. The structural and optical properties are studied by X‐ray diffraction and double beam spectrophotometer, respectively. X‐ray diffraction indicates that the Zn₃N₂ films deposited on Si and quartz glass substrates both have a preferred orientation in (321) and (442), also are cubic in structure with the lattice constant a=0.9847 and 0.9783 nm, respectively. The absorption coefficients as well as the film thickness are calculated from the transmission spectra, and their dependence on photon energy is examined to determine the optical band gap. Zn₃N₂ is determined to be an indirect‐gap semiconductor with the band gap of 2.11(2) eV. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A novel route of synthesis of WS2 thin film and its characterization

WS₂ thin films have been deposited by chemical deposition technique using citric acid as a complexing agent at 343 K. X-ray pattern shows that crystalline nature with hexagonal- and orthorhombic-mixed phase. The films show that good optical properties high absorption and band gap value was found to be 1.31 eV. The specific conductivity of the film was found to be in order of 10⁻³ (Ω cm)⁻¹.     

Synthesis and optical properties of CuInS2 thin films prepared by sulfurization of electrodeposited Cu‐In layers

The chalcopyrite CuInS₂ thin film was fabricated at 500 °C for 2 h by sulfurization of Cu‐In layers (as precursors) that were sulfurized in a glass tube with pure sulfur powder. The structural, morphological, and optical properties of CuInS₂ thin films are characterized using X‐ray diffraction (XRD), field‐emission scanning electron microscope (FE‐SEM), and UV/Visible/NIR spectrophotometer. The study of UV/Visible/NIR absorption shows the band gap energy value of CuInS₂ thin films is 1.5 eV. The XRD pattern shows the film is pure CuInS₂; no other peaks, such as CuS or CuIn₅S₈ were observed. Furthermore, the surface of the CuInS₂ film is compact characterized by FE‐SEM, which also shows the disappearance of CuS on the surface at 500 °C.     

Optical characterization of thermally evaporated thin CdO films

Cadmium Oxide films have been prepared by vacuum evaporation method on a glass substrate at room temperature. Detailed structural, optical, and electrical properties of the films are presented at different annealing temperatures. The crystal structure of the samples was studied by X‐ ray diffraction. The spectral absorption coefficient of the CdO film at the fundamental absorption region (450‐650nm) was determined using the spectral data of transmittance. The direct and indirect band gap energies were determined and found to be 2.33 eV and 1.95 eV respectively. The third order optical nonlinearities χ(3) of CdO films has been measured used the z‐can technique. The real and imaginary parts of χ(3) have been measured at 514 nm and found to be 1.7x10^‐3 esu and 3.0x10^‐3 esu, respectively. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The network structure of amorphous silicon-carbon alloy

The network structure of amorphous silicon-carbon alloy (a-Si_1−xC_x) has been studied over a wide range of x. The a-Si_1−xC_x thin films were prepared by sputtering silicon and carbon target with argon in radio-frequency magnetron sputtering equipment. The films were characterized by X-ray photoelectron spectroscopy, optical absorption, infrared absorption, and mechanical measurements. The results showed that the network structure could be classified neither as the random covalent network nor as the chemically ordered covalent network. The structure as a whole was close to the random covalent network, but the Si-Si combination at x>0.5 showed a feature of the chemically ordered covalent network. The film at 0.6<x<0.8 was hard and showed a high energy gap, due to the sp³ configuration in Si-C combinations.     

Photoinduced structural changes in antimony polyphosphate based glasses

A photocontraction effect in amorphous films of the binary glass system 0.20 [Sb(PO₃)₃]_n–0.80 Sb₂O₃ has been observed after UV irradiation using the 350.7 nm Kr⁺ ion laser line with 5.0 W/cm². Good optical quality films up to 4.0 μm were deposited on silica substrates at room temperature in vacuum by electron beam physical vapor deposition (EB-PVD) and characterized using WDX, XRD, optical absorption, infrared reflectance, profilometry and atomic force microscopy (AFM) techniques. Very stable glasses were prepared by the melt quenching technique and used as evaporation source for the production of films. The photoinduced structural change (PSC) was observed as a variation of about 6% in the film thickness and this effect is accompanied by a photobleaching of the irradiated area with a blue shift of the optical absorption edge. Otherwise this photoinduced change in the film thickness is very sensitive to the variations in the shape and intensity of the laser beam; therefore several possibilities in optical recording arise from these results.     

Synthesis and optical properties of MPTMS-capped CdS quantum dots embedded in TiO2 thin films for photonic applications

CdS nanoparticles have been prepared via a colloidal route using 3-mercatopropyltrimethoxysilane as a capping agent. The stability of the particles in solution and embedded in TiO₂ matrices has been followed by optical absorption. Both the size and the size distribution of the particles are well controlled, thus allowing a tunable emission. Raman and photoluminescence spectroscopies have been used to characterize colloidal CdS, TiO₂:CdS solutions and thin films deposited on soda-lime slides. The Z-scan technique has been used to measure the non-linear refractive indices of the solutions and the non-linear absorption coefficients of the thin films.     

Substrate effect on microstructure and optical performance of sputter‐deposited TiO2 thin films

This study deals with the role of the different substrates on the microstructural, optical and electronical properties of TiO₂ thin films produced by conventional direct current (DC) magnetron sputtering in a mixture of pure argon and oxygen using a Ti metal target with the aid of X–ray diffractometer (XRD), ultra violet spectrometer (UV–vis) and atomic force microscopy (AFM) measurements. Transparent TiO₂ thin films are deposited on Soda lime glass, MgO(100), quartz and sitall substrates. Phase purity, surface morphology, optical and photocatalytic properties of the films are compared with each other. It is found that the amplitude of interference oscillation of the films is in a range of 77‐89%. The transmittance of the film deposited on Soda lime glass is the smallest while the film produced on MgO(100) substrate obtains the maximum transmittance value. The refractive index and optical band gap of the TiO₂ thin films are also inferred from the transmittance spectra. The results show that the film deposited on Soda lime glass has the better optical property while the film produced on MgO(100) substrate exhibits much better photoactivity than the other films because of the large optical energy band gap. As for the XRD results, the film prepared on MgO(100) substrate contains the anatase phase only; on the other hand, the other films contain both anatase and rutile phases. Furthermore, AFM images show that the regular structures are observed on the surface of all the films studied. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optical properties and synthesis of CuInSe2 thin films by selenization of Cu/In layers

In this paper, we report the effect of annealing temperature on the properties of copper indium diselenide (CuInSe₂) thin films. The CuInSe₂ thin films were fabricated at 500 °C for 2 h by annealing Cu‐In layers (as precursors) selenized in a glass tube with pure selenium powder. The structural and morphological properties of the CuInSe₂ thin films were characterized respectively by means of x‐ray diffraction (XRD) and field‐emission scanning electron microscope (FE‐SEM). The type of CuInSe₂ thin film has been identified as direct allowed and the band gap value was determined. The study of UV/Visible/NIR absorption shows that the band gap value of CuInSe₂ thin film is about 1.07 eV, which is within an optimal range for harvesting solar radiation energy. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Characterization of optical properties of amorphous BaTiO3 nanothin films

Amorphous barium titanate nanothin films were prepared by sol–gel dip-coating method. According to transmission spectrum, the refractive index and optical band gap of nanothin films have been determined. High transmission spectrum without any fluctuation in visible wavelength region was recorded. Experimental results indicated that the surface morphology of prepared nanothin films were improved and as a result of that, a better optical properties, less optical losses and higher band gap width were obtained in contrast with other reported data. It was found that optical propagation loss of BaTiO₃ nanothin film was much lower than normal polycrystalline BaTiO₃ thin film. It seems to us that, amorphous barium titanate nanothin films would be suitable for several applications.     

Optical band gap and refractive index dispersion parameters of In-Se-Te amorphous films

Different compositions of In_x(Se_0.75Te_0.25)_100 − x (where 0 ≤ x ≤ 10 at.%) chalcogenide glasses were prepared by the usual melt quench technique. Chalcogenide thin films of these glasses were prepared by using thermal evaporation method. The film transmittance (T(λ)) at normal incidence for these films was measured in the wavelength range 400-2500 nm using a double beam spectrophotometer. Successfully applying Swanepoel's method helps us to determine the film thickness and the real (n) and imaginary (k) parts of the complex index of refraction with high accuracy. Optical absorption measurements show that, the fundamental absorption is due to the allowed non-direct transitions. It was found that, the addition of In content leads to the increase of the refractive index increases while the optical band gap decreases. The obtained results are well discussed in terms of the chemical bond approach and the cohesive energy.     

Optical properties and structure of thin films from the system GeSe2-Sb2Se3-AgI

Chalcohalide glasses from the GeSe₂-Sb₂Se₃-AgI system were synthesized by taking preliminary prepared GeSe₂, Sb₂Se₃ and AgI in their molecular percentages and melting them in an evacuated quartz ampoule. Thin films from the above system were deposited using vacuum thermal evaporation at different conditions on optical glass substrates BK-7. Using X-ray microanalysis it was found that the film composition differs in a certain degree from the bulk composition. Optical transmission and reflection measurements were carried out in the spectral range 400-2500 nm. The optical constants of films thicker than 400 nm (refractive index, n, and absorption coefficient, k) and the film thickness (d) were calculated using a method developed by Konstantinov. The values of n change from 2.38 for thin GeSe₂ films up to 3.48 for thin Sb₂Se₃ films while the optical band gap decreased from 1.92 eV to 1.29 eV, respectively. After exposure to light the photo-induced changes in the optical parameters were negligible for GeSe₂ and Sb₂Se₃ films and increase for some of the ternary samples. Using IR spectroscopy some conclusions about changes in the film structure were drawn.