Influence of thermal annealing on electrical and optical properties of indium tin oxide thin films

Transparent conducting indium tin oxide (ITO) thin films with the thickness of 300 nm were deposited on quartz substrates via electron beam evaporation, and five of them post-annealed in air atmosphere for 10 min at five selected temperature points from 200 °C to 600 °C, respectively. An UV–vis spectrophotometer and Hall measurement system were adopted to characterize the ITO thin films. Influence of thermal annealing in air atmosphere on electrical and optical properties was investigated in detail. The sheet resistance reached the minimum of 6.67 Ω/sq after annealed at 300 °C. It increased dramatically at even higher annealing temperature. The mean transmittance over the range from 400 nm to 800 nm reached the maximum of 89.03% after annealed at 400 °C, and the figure of merit reached the maximum of 17.79 (Unit: 10⁻³ Ω⁻¹) under the same annealing condition. With the annealing temperature increased from 400 °C to 600 °C, the variations of transmittance were negligible, but the figure of merit decreased significantly due to the deterioration of electrical conductivity. With increasing the annealing temperature, the absorption edge shifted towards longer wavelength. It could be explained on the basis of Burstein–Moss shift. The values of optical band gap varied in the range of 3.866–4.392 eV.     

The annealing effect for structural, optical and electrical properties of dysprosium–manganese oxide films grown on Si substrate

Samples of (Dy–Mn) oxide thin films were prepared on quartz and Si(p) substrates for optical and electrical investigations. These samples were annealed at different temperatures and characterised by UV–VIS absorption spectroscopy, X-ray fluorescence (XRF) and X-ray diffraction (XRD). The XRF spectrum was used to determine the weight fraction ratio of Mn to Dy in the prepared samples. The XRD shows that Dy oxide and Mn oxide prevent each other to crystallise alone or making a solid solution even at 600 °C. However, compound of DyMnO₃ was formed through the solid-state reaction for T > 800 °C. The ac-conductance and capacitance were studied, as a function of frequency and gate voltage and the fixed and interface charge densities were determined. It was found that the “correlated barrier hopping” CBH model controls the frequency dependence of the conductivity, while the Kramers–Kronig (KK) relations explain the frequency dependence of the capacitance. The parameters of CBH model were determined and show that the ac-conduction in crystalline (Dy–Mn) oxide is realised by bipolaron mechanism, where the barrier height of hopping is equal to the bandgap determined the UV–VIS absorption spectroscopy.     

Influence of working pressure on the structural,optical and electrical properties of sputter deposited AZO thin films

Highly oriented crystalline aluminum doped zinc oxide (AZO) films were sputter deposited on glass substrates and a systematic investigation on the as deposited and etched films was reported for its further application in silicon thin film solar cell. Influence of the deposition pressure (from 2 to 8 mTorr) and post-annealing temperature (at 400 °C for 5 min) on the structural, optical and electrical properties of the as-deposited and etched samples were analyzed. The optimum condition for its reproducibility and large area deposition is determined and found that the depositions made at 8 mTorr at 200 W having the distance from source to substrate of 9 cm. All the AZO films exhibited a c-axis preferred orientation perpendicular to the substrate and their crystallinity was improved after annealing. From the XRD pattern the grain size, stress and strain of the films were evaluated and there is no drastic variation. Optical transmittance, resistivity, Hall mobility and carrier concentration for the as deposited and etched-annealed films were found to improve from 79 to 82%; 2.97 to 3.14×10⁻⁴ Ω cm; 25 to 38 cm²/V s; 8.39 to 5.96×10²⁰/cm³ respectively. Based on the triangle diagram between figure of merit and Hall mobility, we obtained a balance of point between the electrical and optical properties to select the deposition condition of film for device application.     

Influence of oxygen flow rate on microstructural,electrical and optical properties of indium tin tantalum oxide films

Indium tin oxide (ITO) and indium tin tantalum oxide (ITTO) films were deposited on glass substrates by magnetron sputtering technology with one or two targets. Properties of ITO and ITTO films deposited at different oxygen flow rates were contrastively studied. Ta-doping strengthens along the orientation of (400) plane and leads to better crystalline structure as well as to a decrease in surface roughness. The increase in oxygen flow rate increases sheet resistance and reduces carrier concentration, and ITTO films show higher carrier concentration. Certain oxygen flow rates can improve the visible light transmittance of films, but excessive oxygen can worsen the optical properties. The carrier concentration has an important influence on near-IR reflection, near-UV absorption and optical band gap. The optical band gap decreases with the increasing of oxygen flow rate, and ITTO films show wider optical band gap than ITO films. ITTO films prepared by co-sputtering reveal better optical–electrical properties and chemical and thermal stability than ITO films.     

Effect of annealing on structural,optical and electrical properties of pulse electrodeposited tin sulfide films

Polycrystalline tin sulfide (SnS) thin films were grown on conducting glass substrates by pulse electrodeposition. The effect of annealing on the physical properties such as structure, morphology, optical, and opto-electronic properties were evaluated to understand the effect of post-deposition treatment for SnS films. Annealing at temperatures higher than 250 °°C resulted in the formation of SnS₂ as a second phase, however, no significant grain growth or morphological changes were observed for films after annealing at 350 °C. A small change in band gap of 0.1 eV observed for films annealed at 350 °C was interpreted as due to the formation of SnS₂ rather than due to morphological changes. This interpretation was supported by X-ray diffractometry, scanning electron microscopy, and Raman spectral data. The electric conduction in the films is controlled by three shallow trap levels with activation energies 0.1, 0.05, and 0.03 eV. The trap with energy 0.03 eV disappeared after annealing at higher temperature, however, the other two traps were unaffected by annealing.     

Influence of annealing temperature on the structural and optical properties of nanocrystalline zirconium oxide

Nanocrystalline zirconium oxide powder was prepared by sol-gel method using zirconyl chloride octahydrate (ZrOCl₂·8H₂O) and ethylenediaminetetraacitic acid (EDTA) in ammonium hydroxide (NH₄OH) solution. The as-synthesized complex product was annealed at 650 °C, 750 °C and 850 °C for 2 h to get fine ZrO₂ powder. These samples were further analyzed by Scanning electron microscopy (SEM), X- ray diffraction (XRD), Energy-dispersive X- ray spectroscopy (EDX), UV-vis analysis, Fourier transform infrared (FT-IR) spectroscopy, Photoluminescence spectroscopy (PL) and Raman Spectroscopy to study their structural and optical properties. The structural studies revealed that nanocrystalline ZrO₂ powder exhibits monoclinic phase with variation in crystallite size with annealing temperature. The UV–vis absorption band edge of ZrO₂ decreases from 514 nm to 451 nm as annealing temperature rises from 650 °C to 750 °C. It seems that the drastic reduction in band gap energy may be one of the novel unexpected characteristics of ZrO₂. The FTIR analyses further confirmed the formation of nanocrystalline monoclinic ZrO₂. PL analysis revealed the novel emission peaks at 305 and 565 nm. The Raman spectroscopy confirmed the transformation of amorphous zirconium hydroxide to m-ZrO₂ with increase in temperature from 650 °C to 850 °C.     

Influence of substrate temperature and post deposition annealing on the properties of vacuum deposited ZnSe thin films

The effects of substrate temperature and post deposition annealing on the structural, optical and electrical properties of vacuum deposited ZnSe thin films are presented here. The chemical composition of the films varied drastically with substrate temperature which in turn caused changes in various properties of the films. The grain size of the films increased with substrate temperature and also after annealing. The electrical properties of the films were found to be varying as a function of chemical composition and grain size.     

Effect of co-doping concentration on structural,morphological, optical and electrical properties of aluminium and indium co-doped ZnO thin films deposited by ultrasonic spray pyrolysis

In this work, we reported a chemical approach to prepare aluminium and indium co-doped ZnO thin films (AIZO) by ultrasonic spray pyrolysis. Film depositions were carried out on soda lime glass substrates at 425 °C by using a spray solution containing zinc acetate as zinc precursor, aluminium acetylacetonate as Al dopant source and indium (III) acetate as In dopant source. Physical properties such as structural, morphological, optical and electrical properties were studied with respect to the equal variations in co-dopants concentration (0.5–3 at%). X-ray diffraction patterns proved that films are poly crystalline with (002) preferential orientation. Scanning electron microscopy analysis showed that AIZO films grown like hexagonal nanopyramids, elongated grains and irregular trigonals. Optical transmittance ~85% and a minimum resistivity of 1.3×10⁻³ Ω cm, are achieved for films when co-doped with 1.5 at% of Al and 1.5 at% of In, confirm that AIZO films are suitable for transparent conductive oxide (TCO) applications.     

Effects of RF power on the structural, optical and electrical properties of Al-doped zinc oxide films

In this study, we discussed the effects of growth parameters on the structural and optical properties of Al-doped zinc oxide (AZO) deposited at room temperature by radio-frequency magnetron sputtering. The AZO films have been characterized in detail using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy, Hall-effect measurement system and UV-visible spectrophotometer. It was found that the morphological, structural, electrical and optical properties of AZO films are greatly dependent on sputtering power. Collision between sputter species and surface morphology play important roles in optoelectrical properties of AZO films. According to our experimental results, the AZO films can be used in versatile devices to meet various requirements.     

Effect of fluorine doping on the structural,optical and electrical properties of spray deposited cadmium stannate thin films

Cadmium stannate (Cd₂SnO₄) thin films were coated on Corning 1737 glass substrates at 540 °C by spray pyrolysis technique, from the aqueous solution of cadmium acetate and tin (II) chloride precursors. Fluorine doped Cd₂SnO₄ (F: Cd₂SnO₄) thin films were prepared by adding ammonium fluoride in the range of 0–5 wt% of the total weight of cadmium acetate and tin (II) chloride in the spray solution. Thickness of the prepared films is about 300 nm. X-ray diffraction analysis of the Cd₂SnO₄ and 3 wt% F: Cd₂SnO₄ films shows the signature for the growth along (222) direction. Scanning electron micrographs showed that fluorine doping effectively modifies the surface morphology of Cd₂SnO₄ films. Average optical transmittance in the visible region (500–850 nm) for Cd₂SnO₄ is ~79% and it is increased to ~83% for 1 wt% doping concentration of the NH₄F in the solution. Fluorescence spectra of F: Cd₂SnO₄ (1 wt% and 3 wt%) exhibit peak at 601 nm. F: Cd₂SnO₄ film (1 wt%) shows mobility of ~42 cm²/V s, carrier concentration of ~9.5×10¹⁹ cm^?3 and resistivity of ~1.5×10^?3 Ω cm.     

Impact of substrate temperature on the structural,optical and electrical properties of thermally evaporated SnS thin films

Tin Sulfide thin films were deposited on soda lime glass substrates at three different substrate temperatures using thermal evaporation technique. The impact of substrate temperature on the deposited films has been studied thoroughly. Surface morphology was modified with the substrate temperature. XRD spectra shows orthorhombic end-centered type SnS having (1 1 0) orientation. The crystallite size increases with the increase in the substrate temperature. At a high substrate temperature (450 °C) small grains form on the surface and crystallinity decreases. The effect of substrate temperature on optical and electrical properties has been studied using UV–Vis–NIR Spectrophotometer and Hall effect respectively. With the increase in the substrate temperature there is a substantial decrease in the transmittance and bandgap value. Refractive index (n), dielectric constant (ε₁) and extinction co-efficient (k) have also been calculated for different substrate temperatures.     

Effect of annealing temperature on structural,electrical and optical properties of spray pyrolytic nanocrystalline CdO thin films

Nanocrystalline CdO thin films were prepared onto a glass substrate at substrate temperature of 300 °C by a spray pyrolysis technique. Grown films were annealed at 250, 350, 450 and 550 °C for 2.5 h and studied by the X-ray diffraction, Hall voltage measurement, UV-spectroscopy, and scanning electron microscope. The X-ray diffraction study confirms the cubic structure of as-deposited and annealed films. The grain size increases whereas the dislocation density decreases with increasing annealing temperature. The Hall measurement confirms that CdO is an n-type semiconductor. The carrier density and mobility increase with increasing annealing temperature up to 450 °C. The temperature dependent dc resistivity of as-deposited film shows metallic behavior from room temperature to 370 K after which it is semiconducting in nature. The metallic behavior completely washed out by annealing the samples at different temperatures. Optical transmittance and band gap energy of the films are found to decrease with increasing annealing temperature and the highest transmittance is found in near infrared region. The refractive index and optical conductivity of the CdO thin films enhanced by annealing. Scanning electron microscopy confirms formation of nano-structured CdO thin films with clear grain boundary.     

沉积预制层衬底温度对CIGS薄膜结构特性的影响

采用三步共蒸发工艺在玻璃衬底上制备CIGS薄膜, 研究沉积预制层的衬底温度对CIGS薄膜 结构特性的影响。薄膜的厚度、组份、晶相结构、表观形貌和电学特性分别由台阶仪、X射 线荧光光谱(XRF)、X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)和霍耳效应测量仪来表征。沉积 预制层的衬底温度 较低(如300℃)时,预制层中Ga含 量较低,容易形成In₂Se₃相;而衬底温度较高(如400℃) 时,预制层中Ga含量较高,容易形成(In,Ga)₂Se₃相;原因是Ga₂Se₃的形成焓(－462.4kJ/mol)比In₂Se₃的(－360kJ/mol)低,没有In₂Se₃稳定;In₂Se₃相比Ga₂S e₃相更容易稳定存在,尤其是在低温下;当温度较高 时,Ga₂Se₃相也容易存在,与In₂Se₃一起形成(In,Ga)₂Se₃固溶体。而且,衬 底温度较高(如400℃)时,沉积 的CIGS薄膜中的Ga含量比其它两种衬底温度下沉积的薄膜都高,薄膜粗糙度较小,迁移率和 载流子浓度都比较大,电阻率较小。     

Structural, optical and electrical properties of zinc oxide thin films deposited by a spray pyrolysis technique

Zinc oxide (ZnO) thin films were deposited on glass substrates by spray pyrolysis technique decomposition of zinc acetate dihydrate in an ethanol solution with 30 mL of deposition rate, the ZnO thin films were deposited at two different temperatures: 300 and 350 ℃. The substrates were heated using the solar cells method. The substrate was R217102 glass, whose size was 30 × 17.5 × 1 mm³. The films exhibit a hexagonal wurtzite structure with a strong (002) preferred orientation. The higher value of crystallite size is attained for sprayed films at 350 ℃, which is probably due to an improvement of the crystallinity of the films at this point. The average trans mittance of obtain films is about 90%-95%, as measured by a UV-vis analyzer. The band gap energy varies from 3.265 to 3.294 eV for the deposited ZnO thin film at 300 and 350 ℃, respectively. The electrical resistivity measured of our films are in the order 0.36 Ω·cm.     

Effect of tantalum doping on the structural and optical properties of RF magnetron sputtered indium oxide thin films

Tantalum doped indium oxide films are prepared by RF magnetron sputtering technique and the films are annealed in air at 300 °C. The effect of Ta doping on the structural, morphological, and optical properties of the annealed films are studied using techniques like X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), EDX analysis, micro-Raman, UV–visible and photoluminescence spectroscopy and electrical measurements. The XRD patterns present a cubic bixbyite structure for all the films with preferred orientation along the (222) plane. The lattice constant estimation presents a reduction in lattice size with Ta doping. The W–H plot shows a tensile strain for all the films and also indicates the presence of strain induced broadening of the XRD peaks. The Raman spectra present all the characteristic modes of In₂O₃ cubic bixbyite phase. FESEM and AFM images show the uniform and dense distribution of smaller grains in the films. All the films show high transmittance (above 85%) in the 400–900 nm region. Electrical measurement shows a systematic increase of carrier concentration and electrical conductivity with increase in Ta doping concentration. Band gap energy increases with increase in Ta doping concentration. All the films show intense PL emission in the UV region.     

Influence of the fabrication conditions of polymorphous silicon films on their structural, electrical and optical properties

The structural, optical, and photoelectric properties of polymorphous silicon films produced by plasma-enhanced chemical vapor deposition from a mixture of monosilane and hydrogen at high pressure are studied. Variations in the pressure of the gas mixture used for film production barely change the Raman spectra of the films, but induce changes in the photoconductivity and in the absorption spectrum obtained by the constant-photocurrent technique. The experimentally observed change in the optical and photoelectric parameters of the films is attributed to some structural changes induced in the films by variations in the deposition parameters.     

Effects of annealing on the structural and optical properties of zinc sulfide thin films deposited by ion beam sputtering

We report the structural and optical properties of ZnS thin films fabricated by ion-beam sputtering. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed a polycrystalline ZnS film with zinc blende phase as manifested by diffraction from the (111), (220) and (311) planes. Annealing resulted in the appearance of a metastable wurtzite phase with a concentration up to 26.6%. An energy bandgap, estimated from absorption spectra, was found to vary between 3.32 and 3.40 eV. The lower energy of this bandgap, as compared to bulk ZnS, is associated with the structural point defects along with mixed zinc blende and wurtzite phases of the polycrystalline ZnS films. Ion beam sputtering deposition can be used to tune the optical bandgap for potential applications in optoelectronic materials.     

Influence of substrate temperature on structural and optical properties of RF sputtered ZnMnO thin films

The ZnMnO thin films were deposited on glass substrates by radio frequency magnetron sputtering method. The properties of ZnMnO thin films were investigated by high-resolution x-ray diffractometer (HRXRD),atomic force microscopy (AFM), UV-Vis spectrometer and room temperature photoluminescence (PL), under the influence of substrate temperature. The substrate temperature was varied from 300, 400 and 500°C. With increasing the substrate temperature, the structure of the films changed from cubic to hexagonal. The cubic ZnMnO thin films grown along [210] direction, while the hexagonal ones grown along [002] direction. The changes in surface morphology provided a proof on the structural transition. Also, decrease and increase of optical band gap is associated with cubic or hexagonal structure of the films.

     

Effect of annealing on the structural, optical and electrical properties of ITO films by RF sputtering under low vacuum level

Indium tin oxide (ITO) thin films were prepared by RF sputtering of ceramic ITO target in pure argon atmosphere at a high base pressure of 3×10⁻⁴ mbar without substrate heating and oxygen admittance. The use of pure argon during deposition resulted in films with high transparency (80-85%) in the visible and IR wavelength region. The films were subsequently annealed in air in the temperature range 100-400 °C. The annealed films show decreased transmittance in the IR region and decreased resistivity. The films were characterized by electron microscopy, spectrophotometry and XRD. The predominant orientation of the films is (2 2 2) instead of (4 0 0). The transmission and reflection spectra in the wavelength range 300-2500 nm are used to study the optical behaviour of the films. The optical transmittance and reflectance spectra of the films were simultaneously simulated with different dielectric function models. The best fit of the spectrophotometric data was obtained using the frequency-dependent damping constant in the Drude model coupled with the Bruggeman effective medium theory for the surface roughness. It has been found that the sputtering power and the chamber residual pressure play a key role in the resulting optical properties. This paper presents the refractive index profile, the structure determined from the XRD and the electrical properties of ITO films. It has been found from the electrical measurement that films sputtered at 200 W power and subsequently annealed at 400 °C have a sheet resistance of 80 Ω/□ and resistivity of 1.9×10⁻³ Ωcm.     

Influence of magnesium doping on the structural and optical properties of tin (II) oxide thin films deposited by electron beam evaporation

Single-phase polycrystalline magnesium-doped tin oxide (Mg_xSn_1?xO; x=0, 0.04, and 0.08) thin films were deposited by electron beam evaporation on the glass substrate. X-ray diffraction analysis showed that the peaks intensity of the polycrystalline α-SnO thin films increased along with the increasing Mg content. The crystallite size calculated from X-ray diffraction data decreased by increasing the Mg doping concentration, which was also confirmed by atomic force microscopy. The stoichiometry and thickness of the thin films were determined by Rutherford backscattering spectroscopy. An increase in both the optical transmission (57–95%) and band gap (2.5–2.82 eV) of the Mg_xSn_1?xO thin films were observed which were investigated by UV–vis spectroscopy. Photoluminescence of Mg_xSn_1?xO thin films revealed that there were two extra peaks at 482 nm and 550 nm due to the crystal defects introduced by the Mg doping and these peaks become weaker and shifted to longer wavelength by increasing the Mg doping concentration.