Where N is the carrier concentration, µ is the mobility and e is electronic charge. The result from Hall measurement of the prepared films is tabulated in table 2. Indiumdoping has improved the conductivity of the ZnO film by up to two orders. The improvement in conductivity can be attributed to the additional free carriers generated by doping. 2 at% indium doped films show minimum resistance of 1.986 X10 -2 Ωcm. The variation of sheet resistance, carrier mobility and carrier concentration with indiumdoping is graphically presented in Figure 2.Despite the increase in carrier concentration the sheet resistance increased for IZO-4, with respect to IZO-2, owing to the low free carrier mobility in IZO-4. The carrier concentration reduces with further Increase in the indiumdoping concentration. Similar effect has been reported for zirconium doped zinc oxide 25 . At high level doping the dopant atoms form some kind of neutral defects which do not contribute to carrier concentration. Instead they agglomerate at grain boundaries and suppress the grain growth and result in smaller grains 26 .
The chemical compositions and chemical bond states of the thinfilms were characterized using X-ray photo- electron spectroscopy (XPS). XPS analysis was carried out through a scientific spectrometer (Axis Ultra DLD) with an Al KR X-ray source (1486.6 eV). The phase and crystallinity of samples were measured by X-ray diffrac- tion (XRD; Bruker D8 ADVANCE) with Cu Kα radiation (λ = 1.5418 Å). The images of atomic force microscopy (AFM) of samples were obtained by using a Bruker Dimension Icon microscope VT-1000 System operated in tapping mode. The spectroscopic ellipsometry measure- ment was carried out by a vertical variable-angle SE (V-VASE; J.A. Woollam Co., Inc.) in the wavelength range of 200–1000 nm with a spectral resolution of 5 nm. The incident angle was selected as 65, 70, and 75° to insure the reliability of fitting results. Optical transmission spectra were measured with a double beam UV-VIS-NIR spectro- photometer (Shimadzu UV-3600) in the wavelength range of 250–1000 nm. And the electricalproperties of the films were measured by using thevan der Pauw method with a Hall effect measurement system (Ecopia HMS3000). All these measurements were carried out at room temperature.
In this study Mg doped ZnOthinfilms in various concentrations were fabricated on microscope glasses using the spin coating method and the opticalproperties of these samples were investigated by using XRD, SEM and UV-Vis spectra. It has been found that for all Mg doping concentrations, ranging from 0% to 100%, crystal structures have been attained. From the XRD spectra it has been found that the thinfilms inhibit both the ZnO and the MgO semiconductor crystal structures together within the film matrices as their diffraction peaks pre- sented in the spectra and the doping concentrations reflect themselves in the peak heights, therefore the presence of one has not any impact of suppressing the other’s intensity. We have managed to produce MgO and ZnO grains together inside the film matrix which, to our knowledge, is the first appearance of these kind of empirical processes in the literature. From these serial experiments one may realize that it is likely to produce various metal doped thin film structures which might inhibit very interesting opticalproperties in the area of photonics.
The characteristic properties of cobalt and manganese doped ZnOthinfilms were analyzed and studied in the present work. Cobalt and manganese doped ZnO nano rods had been successfully synthesized in a dip coating method at low growth temperature of 90°C for three different molar concentration of 1%, 2% and 3% and annealed at 500°C. The crystalline structure, morphology and opticalproperties were investigated. The films had good adherence to the substrate. In XRD, at lower concentration of Co doping, the X-ray diffraction pattern showed that the ZnOthinfilms possess the hexagonal wurtzite structure. As concentration increases, the wurtzite structure collapsed and turned into flake like structures which is seen in SEM. In Mn doping, as concentration increases, the width of the nanorods decreased. In UV absorption, the intensity of the absorption edge shifts to a higher wavelength in both cobalt and manganese doped ZnO. In UV transmission, a slight decrease in the percentage of the transmission is seen in both the cases. Finally from the results, it clearly indicates that, in both Co and Mn doping with ZnO, the lower concentration gives better results. These prepared Co and Mn doped ZnOthinfilms can be sued for magnetic materials.
The X-ray pattern shows that there is no change in the intensity of peaks with dopant concentration. The lattice constant (a) of the samples were calculated. The effective ionic radius of Ga 3+ ion (0.62Å) is slightly larger than Ti 4+ (0.61Å), so it enters into B-sites and gets substituted in the place of Ti 4+ ions. High temperature annealing in air can promote the lattice parameters to increase . The films preheated at 400ºC and annealed at 800ºC may be responsible for the increase in lattice parameters. The increase in lattice parameters of Ga doped BST thinfilms were clearly observed as the 2θ peak shifted toward lower angle in compared with undoped BST thinfilms. The crystallite size and lattice strain of the deposited films were evaluated by using Williamson–Hall plots. W–H plots were drawn with sinθ in x- axis and βcosθ in the y-axis that was shown in Fig.2. From the linear fit of the data, the slope determines the lattice strain (ε) and the intercept determines the crystallite size (D) (Eq.1) 
O) thinfilms, where x = 0, 4, 6 and 8 % have been successfully deposited on glass substrates by chemical spray pyrolysis (CSP) technique at substrate temperature of (400 °C) and thickness of about 300 nm. The structural and opticalproperties of these Visible spectroscopy. The XRD results showed that all films are polycrystalline in nature with Hexagonal structure and preferred orientation along 03) planes. The crystallite size was calculated using Scherrer’ ZnO sample has maximum crystallite size (23.11nm). AFM results showed homogenous and smooth thinfilms. The absorbance and transmittance spectra have 900) nm in order to study the opticalproperties. The optical energy gap for allowed direct electronic transition was calculated using Tauc equation. It is increases and the band gap values were in The optical constants including (absorption coefficient, real and imaginary parts of dielectric constant) were also calculated as a function of photon energy. Refractive index and
127.6) and (In = 114.818) by using sensitive electrical balance type (AE 166 Metter), then mixing these ele- ments. Quartz tube is carefully cleaned in order to remove dust, grease and other possible contaminants, then putting this mixture in it (height of the tube equals to 10 cm and diameter equal 15 mm) which is evacuated until pressure reached ≈ (10 −2 Torr), the tube is sealed and put in electric furnace of type SRJX-5-13 Model Box-Re-
We have used sol-gel process as a simple low-cost technique for the preparation of IZO thinfilms. It can be concluded that indium acts as an effective donor in zinc oxide up to a certain concentration and supplies a single free electron resulting from In 3+ ion on a substitutional site of Zn 2+ . The properties of the resultant material are sensitive to processing conditions. In particular, the conductivity of the films depends strongly on the subsequent heat treatment. The requirement of vacuum annealing treatment to reduce resistivities by an order of magnitude has been established. It was determined that the out-diffusion of oxygen during the sample vacuum annealing was a determinant factor directly associated with the electrical activity of the dopant. Regardless of their nature and composition, the presence of neutral defects may play a decisive role that justifies the regress of the meas- ured mobility especially at high indium content. Relatively more densely packed films are obtained when sub- jected to vacuum annealing regardless of the dopant level. Very transparent films can be obtained. The band gap shift remains below that theoretically predicted, probably due to the high concentration of neutral impurities. The effect of these impurities on band-gap narrowing should be considered with the electron-electron and elec- tron-ion scattering.
For Fluorine-Doping Ammonium Fluoride (NH4F) disintegrated in doubly refined water was added to the starting arrangement. Though for Antimony-Doping Antimony-Trichloride (SbCl3) broke up in isopropyl liquor was included. The general measure of arrangement for each situation was set up to 50 ml and a similar measure of arrangement was showered on pre-warmed substrates. The rehashed analyses of every affidavit demonstrated that the films could be repeated effortlessly. A broad care was taken in giving adequate splash interim between progressive showers for the substrates return to statement temperature in the wake of experiencing warm deterioration. This has brought about the best possible decay of the films that thus delivered the most minimal ever sheet opposition esteems revealed for the doped SnO 2 films from SnCl2 antecedent. The
devices, transparent electrodes, and solar cells [5 – 7]. Controlling of ZnO physical properties depending on various factors, such as doping and temperature growth, is important for efficient function of devices on the base of ZnO structures. The existence of both (n and p) conduc- tion types is of fundamental importance for application in light-emitting devices . The nanostructures like nano- tubes, nanorods, nanowalls, nanofibers and high-quality undoped and doped ZnOthinfilms have been grown with plasma-assisted molecular beam epitaxy, vapor transport deposition method, vacuum arc deposition metal organic chemical vapor deposition (MOCVD), sol – gel process, and spray pyrolysis [9, 10]. Such nanotubes, nanowires, nanoribbons, and nanofibers have deserved special atten- tion for their potential applications in applied fields such as field emission displays, optical waveguides, solar cells, ultraviolet photodetectors, optical switches, and gas sensing [1 – 8]. The chemical bath deposition and sol – gel technique are also well known methods of preparation of ZnOthinfilms. Among these methods, spray pyrolysis is useful in wide range of applications [11, 12]. This method is cheaper, simpler and permits to obtain films for opto- electronic applications with required properties. Structural, electrical, and opticalproperties dependence on thickness
Figure 1 shows a relationship between the absorbance (A) and the incident wavelength for undoped Zinc oxide films and doped by Indium of different doping ratios. It was noted that the values of absorbance decrease by the increasing of wavelength , To explain this phenoma , that is related the incident photon energy is less than , the value of the forbidden gap . We can notice also that the absorption shift to word the short wavelength leading to an increase in the value of optical energy gap with the increasing of doping concentration.
optical and electricalproperties of ZnOthinfilms grown by thermal and remote plasma-enhanced atomic layer deposition (Thermal ALD and PEALD) and their applications in resistive switching devices. The conductivity of ZnOfilms grown by Thermal ALD at 200°C is ~62.5 S/cm, demonstrating a good potential for the applications in transparent conducting films. It is possible to deposit ZnOfilms with good structural quality and few defects at lower temperatures by PEALD. The Al/PEALD-ZnO/Pt devices show good resistive switching properties, while the devices using Thermal ALD ZnOfilms failed to show any resistive switching behavior, but a perfect Ohmic behavior. The thickness ZnO active layer has a strong effect on the device properties. When the thickness of ZnO film is ~23 nm, the high state-resistance to low state-resistance ratio maintains at larger than 10 3 , while the current compliance for safe operation is ~1mA much smaller than those for devices with thick active layers. The results have demonstrated the PEALD grown ZnOfilms have the excellent properties for the applications in high-density 3D resistive random access memory.
ZnOthinfilms can be prepared by a variety of methods like chemical and physical deposition methods namely sputtering, pulse laser deposition etc . Chemical deposition methods are relatively simpler and cost effective. However, for commercial application, it is necessary to develop a low temperature deposition technology for the growth of ZnOfilms . ZnOthinfilms synthesized using SILAR technique has the advantages of being effective and simple. SILAR is a wet chemical route for the synthesis of thinfilms in which the basic building blocks are ions where the preparative parameters are easily controllable. DopingZnO with transition metal (Co) exhibits wide direct bandgap (3.37 eV), high exciton binding energy (60 meV), low cost, non- toxicity, and stability over a wide temperature range [3-5]. Cobalt complexes show interesting antibacterial, antimicrobial, antitumor, and many other biological activities . In the present study, ZnO and Co doped (3%, 5%, 7%) ZnOthinfilms were deposited on glass substrate by SILAR technique annealed at 250ºC. The structural, morphology, opticalproperties and antibacterial applications of the ZnO and Co doped ZnOthinfilms have been studied.
In most of these cases, the nanocomposites were fur- ther used in various applications in their thin-film form. Although these PANi-ZnO nanocomposites are also con- ducting since they are polyaniline emeraldine chloride, their processability is still poor to limit their commercial uses although their conductivity could be measured by sandwiching the pellets. PANi doped with organic acids such as CSA, DBSA, PVSA etc. which possesses suffi- ciently strong Bronsted acid centers capable of polyani- line protonation together with suitable functional groups which, when introduced to the polymer matrix upon doping, induce the solubilization of its stiff conjugated backbone, is readily soluble, chemically stable, and elec-
XRD patterns of ZnTe films before and after doping are presented in Fig. 1 . It is observed that as-deposited film prepared at room temperature possesses broad peak indicating amorphous structure. The presence of intense peak at 2 = 25.21 degree in (111) direction for indium doped films reveals that these films are crystalline in nature. The 2 values observed in the XRD and those of JCPDS (01- 0582) data were found in fair agreement between them. Doped films were found to exhibit two diffraction peaks associated with (111) & (220), of which the intensity of (111) orientation is predominant. The lattice parameters of the films were calculated using the Bragg’s formula: 
Abstract: During the last decades, thinfilms of ZnO have given rise to a great interest, as transparent conducting oxides. This is due the optical and electricalproperties of zinc oxide; it’s very high thermal and chemical stability, its non-toxicity as well as his abandonment in nature. The transparent conducting ZnOthinfilms were deposited on glass substrate by pyrolysis spray technique. Zinc acetate was used as starting solution with a molarity of 0.1 M. The structural and opticalproperties of the ZnOthinfilms were studied as a function of the substrate temperatures in the range of 100 to 400°C. Structural properties have been studied by X-ray diffraction (XRD) technique. The preferred orientation for ZnOthinfilms lies along (002) direction. From XRD data, the average crystallite size is determined from scherrer formula. The grain size is in the range of 10~27. The transmittance of the films is enhanced from 60 to 85% in the visible region in the range from 400 to 1100 nm by increasing the substrate temperature. The optical band gap energy attenuates from 3.67 to 3.25eV and whereas the Urbach energies of the films increase from 226 to 91.2 meV with increasing the substrate temperature from 100°C to 400°C.
ZnO semiconducting thinfilms were fabricated using a sol-gel method under standard atmospheric conditions and acetates as precursors. The performances of thin-film transistors (TFT) with a ZnO active channel layer and effects of indiumdoping on the threshold voltage of ZnO TFTs were evaluated at a low temperature (300 ℃). By examining the electrical characteristics of thinfilms and TFTs while doping a ZnO system with increasing indium concentrations from 0.01 to 0.1M, reductions at the threshold voltage of 5.3 V and an increase of an order of magnitude of the on/off current ratio were observed. Oxygen vacancies increase when the indium concentration increases, thus releasing electrons and increasing the channel carrier concentration. At 300 ℃, the indium-doped zinc oxide (IZO) device performance showed a mobility of 0.06 cm 2 /V-s, a threshold voltage of 5.3 V, and an on/off current ratio of 10 6 .
Abstract Annealing treatment of transparent conducting oxide (TCO) thinfilms plays a great role in enhancing the optoelectronic properties of the material. Changes in morphological, optical and electricalproperties of indium tin oxide (ITO) thinfilms deposited by RF sputtering were investigated after exposing the films to Nd:YAG laser radiation. ITO thinfilms of 158 nm thickness were irradiated with different laser energy; 25 mJ, 75 mJ, 120 mJ and 165 mJ respectively. Atomic force microscopy (AFM) results reveal a smooth surface morphology and enhance grain size as the laser energy increases. Highest optical transmittance value of 96.5 % at 620 nm wavelength was obtained by film treated with 165 mJ laser energy as determined by UV-Vis spectrophotometer. Electrical resistivity measurements as determined by four-point probe show a significant decrease in resistivity and sheet resistance with respect to increasing laser energies. The ITO films optoelectronics properties were enhanced with the film annealed at 165 mJ exhibiting the highest calculated figure of merit. This laser treatment method has effectively fine turned the ITO filmsproperties toward TCO functional properties required for solar cell application.
Zinc oxide is highly resistive in its pure form and efforts are made by researchers to improve its electrical conductivity by intentional doping. Selection of the dopant should be based on the ionic size and electro negativity, since these two factors decide the efficiency of the dopant element. High valence group III elements are chosen to enhance the electricalproperties of ZnO. Among those aluminum (AZO) and gallium (GZO) doped ZnO are studied much. There are only few reports on Indium doped ZnO (IZO). Indiumdoping lowers the resistivity of the films, with values ranging from 4.03x 10 -5 to 3x10 -3 Ω cm [7,8].