Indium-doped Zinc Oxide Research Articles

Study of the Structural and Optical Properties of Indium-Doped ZnO on a Glass Substrate for Various Doping Concentration by using Pulsed Laser Deposition

Study of the Structural and Optical Properties of Indium-Doped ZnO on a Glass Substrate for Various Doping Concentration by using Pulsed Laser Deposition

Growth and optical properties of tetrapod-like indium-doped ZnO nanorods with a layer-structured surface

We report tetrapod-like indium-doped ZnO nanorods with a layer-structured surface, synthesized by a thermal vapor transport method. The high crystalline quality of the nanostructure sample obtained was confirmed by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. We carried out photoluminescence and photoluminescence excitation measurements to investigate the possible application of this indium-doped ZnO nanostructure in the field of optical devices. The photoluminescence exhibited an ultra strong visible wavelength emission with a peak intensity 300 times stronger than the band edge ultraviolet emission. In addition, a very slow decay of visible wavelength emission was revealed by time-resolved photoluminescence spectroscopy.

Properties of Indium Doped Zinc Oxide Thin Films Deposited by RF Magnetron Sputtering

Indium doped zinc oxide films (ZIO) were deposited on non-alkali glass substrates by radio frequency (RF) magnetron sputtering at room temperature. The structural, electrical and optical properties of the ZIO films were investigated as a function of their In₂O₃ content (3.33-15.22 wt%). The ZIO films deposited with an In₂O₃ content of 9.54 wt% showed a relatively low resistivity of 9.13×10 ?4 Ω㎝ and a highly c-axis preferred orientation. The grain size and FWHM were mainly affected by the In₂O₃ content. The crystallinity and resistivity were enhanced with increasing grain size. The average transmittance of the ZIO films was over 85% in the visible region and their band gap varied from 3.22 to 3.66 eV depending on their doping ratio.

Growth and characterization of transparent conducting nanostructured zinc indium oxide thin films

Transparent conductive oxide (TCO) films have been widely used in various applications, such as for transparent electrodes in flat-panel displays, and in solar cells, optoelectronic devices, touch panels and IR reflectors. Among these, tin doped zinc oxide (ZTO) and indium doped zinc oxide (ZIO) have attracted considerable attention. Particularly, IZO thin film is the best candidate for high-quality transparent conducting electrodes in OLEDs and flexible displays. In this work zinc indium oxide (ZIO) thin films were deposited on glass substrate with varying concentration (ZnO:In 2O 3 — 100:0, 90:10, 70:30 and 50:50 wt.%) at room temperature by flash evaporation technique. These deposited ZIO films were annealed in vacuum to study the thermal stability and to see the effects on the physical properties. The XRF spectra revealed the presence of zinc and indium with varying concentration in ZIO thin films, while the surface composition and oxidation state were analyzed by X-ray photoelectron spectroscopy. The core level spectra were deconvoluted to see the effect of chemical changes, while the valance band spectra manifest the electronic transitions. The surface morphology studies of the films using atomic force microscopy (AFM) revealed the formation of nanostructured ZIO thin films. The optical band gap was also found to be decreased for both types of films with increasing concentration of In 2O 3.

Indium-doped ZnO nanowires: Optical properties and room-temperature ferromagnetism

We report the optical and magnetic properties of ZnO, Zn0.97In0.03O, and Zn0.94In0.06O nanowires (NWs). All samples have similar wirelike shape with an average diameter of about 70 nm and a length of about 10 μm. The comparison of photoluminescence (PL) spectra at 10 K indicated that a new broad emission band appeared after indium doping, which is associated with donor-acceptor-pair recombination. Additionally, the intensity of oxygen-vacancies-induced visible emission increased with increasing In content, indicating that In doping can induce many oxygen vacancies. Furthermore, magnetic measurements revealed that pure ZnO NWs are diamagnetic, while indium-doped ZnO NWs exhibit intrinsic ferromagnetism at room temperature. With the increase in In content, the coercive field and the magnetic moment for indium-doped ZnO NWs increase largely. Ferromagnetic ordering can be interpreted as being due to O vacancies induced by In doping, which is in good agreement with PL results.

On the structural, morphological, optical and electrical properties of sol–gel deposited ZnO:In films

Indium-doped zinc oxide thin films deposition was performed by the sol–gel technique using homogeneous and stable solutions of zinc acetate 2-hydrate and indium chloride in ethanol. Films were spin coated onto glass substrates. After drying and after a heat treatment at 450 °C, highly transparent (80%–90%) films were obtained. The effect on the structural, morphological, optical and electrical thin films properties of the dopant concentration was investigated. The temperature dependencies of the electrical conductivity under vacuum and in open atmosphere were analysed and discussed.

Comparative effects of indium/ytterbium doping on, mechanical and gas-sensitivity-related morphological, properties of sprayed ZnO compounds

In this study, conducting and transparent indium-doped zinc oxide (ZnO) thin films have been deposited on glass substrates by the micro-spray technique. First, zinc oxide layers were obtained by spaying a solution of propanol and zinc acetate in acidified medium. Alternatively, some of the obtained films were doped with indium (In) at the molar rates of: 1%, 2% and 3%. In addition to the classical structural investigated using XRD, AFM and SEM techniques, microhardness Vickers (Hv) measurements have been carried out along with comparative morphological prospecting. The specific gases sensitivity-related surface morphology of the doped ZnO compounds was favorably different from that of the non-doped ones, and showed a thin overlay structure. Results were compared to those recorded for similar ytterbium-doped material.

Indium-Doped MgxZn1-xO Films for ZnO-Based Heterojunction Diodes

Indium-doped MgxZn1-xO (MgxZn1-xO:In) thin film and ZnO:In thin films were successfully grown by remote plasma-enhanced metalorganic chemical vapor deposition (RPE-MOCVD). The In supply source used is trimethylindium (TMIn). The surface morphology, structural changes, and optical band gap energy in MgxZn1-xO:In were investigated by varying the amount of the supplied TMIn and were compared with ZnO:In systems. Our main achievement point is that we have markedly improved the surface morphology of Mg0.05Zn0.95O:In films from being pillar like to being film like with an increase in the amount of indium. The improved green electoluminescence emission (EL) characteristic the ZnO-based DH system was employing the Mg0.05Zn0.95O:In film here and in conclusions.

An investigation of the microstructure, optical and electrical properties of ZITO thin film using the sol–gel method

The multi-compound ZITO transparent conductive oxide (TCO) thin films were synthesized using the sol–gel method. The ZITO thin films with various volume ratios of ZnO to ITO (1:1, 2:1 and 9:1) were crystallized at different temperatures (600–700 °C). The results showed that the crystalline characteristics and optical transmittance were mainly dependent on ITO content and crystallization. Notably, the 650 °C Z9ITO film not only had better conductivity but also possessed excellent optical transmittance. In addition, the surface roughness of the ZITO films and optoelectric properties of IZO (indium doped ZnO) films were analyzed to confirm the contribution of indium dopants on the optical transmittance. Also, the ZITO films were subjected to the effects of indium and tin dopants and this improved the related characteristics of ZnO films.

One-Step Synthesis of Monodisperse In-Doped ZnO Nanocrystals.

A method for the synthesis of high quality indium-doped zinc oxide (In-doped ZnO) nanocrystals was developed using a one-step ester elimination reaction based on alcoholysis of metal carboxylate salts. The resulting nearly monodisperse nanocrystals are well-crystallized with typically crystal structure identical to that of wurtzite type of ZnO. Structural, optical, and elemental analyses on the products indicate the incorporation of indium into the host ZnO lattices. The individual nanocrystals with cubic structures were observed in the 5% In–ZnO reaction, due to the relatively high reactivity of indium precursors. Our study would provide further insights for the growth of doped oxide nanocrystals, and deepen the understanding of doping process in colloidal nanocrystal syntheses.

Low content indium-doped zinc oxide films with tunable work function fabricated through magnetron sputtering

Low content indium-doped zinc oxide (LC-IZO) films have been prepared through radio-frequency (RF) magnetron sputtering. The work functions of the LC-IZO films were successfully tuned up by modulating the deposited conditions, such as indium content, substrate temperature, bias voltage and film thickness. The work functions of the films may be modulated in a large range between 4.59 eV and 5.56 eV. The change of the work function may be the results induced by the change in the surface state. The results may be helpful for widening the application of LC-IZO films.

Effects of hydrogen annealing on the structural, optical and electrical properties of indium-doped zinc oxide films

Indium-doped zinc oxide (IZO) films were fabricated by radio-frequency magnetron sputtering. The effects of hydrogen annealing on the structural, optical and electrical properties of the IZO films were investigated. The hydrogen annealing may deteriorate the crystallinity of the films. The surfaces of the films would be damaged when the annealing temperature was higher than 350 °C. After the annealing, the surface roughness of the films would decrease, and high transparency of 80–90% in the visible and near-infrared wavelength would be kept. Meanwhile, the resistivity decreased from 1.25 × 10−3 Ωcm of the deposited films to 6.70 × 10−4 Ωcm of the annealed films. The work function of the IZO films may be modulated between 4.6 and 4.98 eV by varying the hydrogen annealing temperature and duration.

Properties of In-Doped ZnO Films Grown by Metalorganic Chemical Vapor Deposition on GaN(0001) Templates

We investigated the properties of indium-doped zinc oxide layers grown by metalorganic chemical vapor deposition on semi-insulating GaN(0001) templates. Specular and transparent films were grown with n-type carrier concentrations up to 1.82 × 1019 cm−3 as determined by Hall measurements, and all In-doped films had carrier concentrations significantly higher than that of a comparable undoped film. For low In flows, the carrier concentration increased accordingly with trimethyl-indium (TMIn) flow until a maximum carrier concentration of 1.82 × 1019 cm−3 was realized. For higher In flows, the carrier concentration decreased with increasing TMIn flow rate. Sheet resistance as low as 185 Ω/sq was achieved for the In-doped films, which is a significant decrease from that of a comparable undoped ZnO film. Our n-type doping studies show that In is an effective dopant for controlling the n-type conductivity of ZnO.

Displacement field measurement of metal sub-lattice in inversion domains of indium-doped zinc oxide

The displacement field of the metal sub-lattice in homologous compounds In 2O 3(ZnO) m is investigated by means of aberration-corrected high-resolution transmission electron microscopy. The elastic state in these compounds is characterised by plane strain where little column bending occurs due to surface relaxation. The compound contains inversion domain boundaries (IDBs) on basal and pyramidal planes of ZnO where the displacements are concentrated. The structure is imaged in <1 1¯ 0 0> of ZnO with negative spherical aberration and using bright atom contrast condition. Local atomic shifts are measured with precision of ca. 5 picometres in real space with a peak finding algorithm. The strain tensor and lattice rotations are calculated from displacements displaying dilatation, shear and rotation at pyramidal IDBs which reveal a mirror plane through the centre of each inversion domain.

Investigation of the physical and electronic properties of indium doped zinc oxide nanofibers synthesized by electrospinning

Nanostructured metal oxides and particularly nanofiber based materials can provide significant advances for the miniaturization of electronic, optoelectronic, photonic, sensor, and energy conversion devices with enhanced performance based on their unique material properties. In this study, indium doped zinc oxide (IZO) nanofibers were synthesized by electrospinning. These nanofibers have diameters in the range 50–100nm. The effects of indium addition on the structural, optical, and electrical properties of the zinc oxide nanofiber matrices were investigated. The IZO nanofibers undergo significant changes in their optical and electrical properties compared to undoped zinc oxide nanofibers.

Weak Localization and Electron−Electron Interactions in Indium-Doped ZnO Nanowires

Single crystal ZnO nanowires doped with indium are synthesized via the laser-assisted chemical vapor deposition method. The conductivity of the nanowires is measured at low temperatures in magnetic fields with directions both perpendicular and parallel to the wire axes. A quantitative fit of our data is obtained, consistent with the theory of a quasi-one-dimensional metallic system with quantum corrections due to weak localization and electron-electron interactions. The anisotropy of the magneto-conductivity agrees with theory. The two quantum corrections are of approximately equal magnitude with respective temperature dependences of T(-1/3)and T(-1/2). The alternative model of quasi-two-dimensional surface conductivity is excluded by the absence of oscillations in the magneto-conductivity in parallel magnetic fields.

H 2S gas sensitive indium-doped ZnO thin films: Preparation and characterization

High quality indium-doped ZnO (IZO) thin films (∼100 nm) have been deposited onto the glass substrates by using a conventional spray pyrolysis technique. Precursors such as zinc acetate, indium chloride with Brij-35 (polyoxyethylene lauryl ether) as a non-ionic surfactant were used. The morphology, crystal structure, elemental analysis and the gas response properties were investigated by using SEM, TEM, XRD, AFM and XPS techniques. The films show hexagonal wurtzite structure which reveal variations in (1 0 0), (0 0 2) and (1 0 1) intensities with indium doping. The crystallite size calculated by Scherrer formula was in the range of 30–50 nm. The SEM and AFM analysis show 50–70 nm sized grains, while the TEM confirms formation of grains by ∼10 nm sized particles. Their response towards various gases was measured at different operating temperatures and different levels of In-dopants. The 3 at% In-doped ZnO showed response as high as 13,000 for 1000 ppm H 2S at 250 °C. It exhibited fast response (∼2 s) and recovery time (∼4 min). The gas response strongly depends on the morphology and indium concentration. The high gas response of IZO is explained on the basis of thickness dependent trap state density.

Indium-doped zinc oxide nanometre thick disks synthesised by a vapour-phase transport process

Indium-doped ZnO nanometre thick disks were successfully fabricated by thermal evaporation of a powder mixture of ZnO, In2O3, and graphite without catalyst. Incorporation of indium metal in the nanodisks during the synthesis was not successful due to the formation of In2O3 phase. SEM images show that some ZnO disks have perfect hexagonal shape. These disks are about 1–5 µm in size and 40–100 nm in thickness. X-ray diffraction, Raman, transmission electron microscopy, and energy dispersive spectroscopy observations show that the disks are single crystalline ZnO with wurtzite structure. Effect of indium doping on the structure, morphology, optical absorption, and photoluminescence of the nanodisks are studied.

Physical properties and growth kinetics of co-sputtered indium-zinc oxide films

Indium-doped zinc oxide (IZO) films were fabricated by radio-frequency (RF) magnetron sputtering through co-deposition of zinc oxide (ZnO) and indium (In) at ambient temperature. Transparency of the IZO films is higher than 80% in the visible range while the optical band gap decreases with increasing In dopant concentration. The optimal measured resistivity, Hall mobility and carrier concentration of the film are 1.39 × 10−3 Ω cm, 10.11 cm2 V−1 s−1 and 5.35 × 1020 cm−3, respectively. The In dopant favors smoothing the film surface. The In dopant concentration in the film decreases vertically from the surface to the interface due to the surface segregation during the kinetic deposition process. The misfit strains of the films are gradually relaxed through dislocation.

Optical sensor with transparent conductive oxides electrodes for microposition detection applications

This paper presents an optical sensor structure for microposition detection application using transparent electrodes of indium doped ZnO (IZO). The optical microsensor consists of two linear arrays of metal – semiconductor – metal (MSM) silicon photodetectors with IZO transparent electrodes integrated with a polymer optical waveguide. IZO layers with a thickness of 460–580 nm have been deposited by dc magnetron sputtering technique on silicon epitaxial wafers of 30–50 Ω cm resistivity and a thickness of 23 µm. Due to their high optical transmittance (> 90%) over the 0.4–0.9 µm spectral range, these layers contributed to an increased responsivity of the MSM photodiode structure of about 0.34 A/W, thus improving the optical position microsensor sensitivity.