Doped In2O3 Research Articles

Metal-Doped In2O3 Nanosphere Arrays with Enhanced Gas-Sensing Property

In2O3 and metal-doped (Ni or Ce) In2O3 mesoporous three-dimensional (3D) nanospheres arrays were synthesized via nanocasting using mesoporous silica as hard templates. Effects of Ni or Ce doping on the structure, optical and gas-sensing properties of the In2O3 nanospheres were investigated. Both the undoped and the doped In2O3 nanospheres showed single-phase structure without any impurity. The nanospheres were about 20[Formula: see text]nm in size and they stacked closely to form rigid 3D mesoporous structure. A change in the value of optical band gap was observed upon metal doping. The room temperature photo luminescence behavior also showed some differences between pure and doped In2O3. Compared with pure In2O3 nanospheres, the metal-doped In2O3 exhibited superior response, fast recovery and good selectivity to ethanol. The enhanced gas-sensing properties might be related to the doping of metal ion and its effective contribution towards the oxygen vacancies, conductivity and crystallite size of the grains.

Polymer Doping Enables a Two-Dimensional Electron Gas for High-Performance Homojunction Oxide Thin-Film Transistors.

High-performance solution-processed metal oxide (MO) thin-film transistors (TFTs) are realized by fabricating a homojunction of indium oxide (In2 O3 ) and polyethylenimine (PEI)-doped In2 O3 (In2 O3 :x% PEI, x = 0.5-4.0 wt%) as the channel layer. A two-dimensional electron gas (2DEG) is thereby achieved by creating a band offset between the In2 O3 and PEI-In2 O3 via work function tuning of the In2 O3 :x% PEI, from 4.00 to 3.62 eV as the PEI content is increased from 0.0 (pristine In2 O3 ) to 4.0 wt%, respectively. The resulting devices achieve electron mobilities greater than 10 cm2 V-1 s-1 on a 300 nm SiO2 gate dielectric. Importantly, these metrics exceed those of the devices composed of the pristine In2 O3 materials, which achieve a maximum mobility of ≈4 cm2 V-1 s-1 . Furthermore, a mobility as high as 30 cm2 V-1 s-1 is achieved on a high-k ZrO2 dielectric in the homojunction devices. This is the first demonstration of 2DEG-based homojunction oxide TFTs via band offset achieved by simple polymer doping of the same MO material.

Synthesis of In(Sn)-O and Sn(In)(Sb)-O System Nanoparticles Using DC Arc Plasma Method

A new DC arc plasma concept was proposed to produce metal oxide nanoparticles by metal melting, blasting or gasification processes. It was exemplified by the preparation of single phase nanoparticles SnO2, In2O3 and SnO2, In2O3-based composite nanoparticles such as In2O3:Sn (ITO), SnO2:Sb (ATO) and SnO2:In:Sb (IATO). X-ray diffraction (XRD) indicates that the doped SnO2 and In2O3 are single phase and there is no other secondary phase. The results of transmission electron microscopy (TEM) show that for the prepared single phase nanoparticles with good dispersion, the particle size ranges from 20 to 50 nm. The prepared ITO and ATO nanoparticles were utilized in ITO target and ATO electrode, and their density and electrical properties were tested. The prepared ITO target and ATO electrode have high density and low resistivity, and the ITO target has good film-forming effect, which implies that the ITO and ATO nanoparticles prepared by DC arc plasma can be applied to the field of flat panel displays and conductive electrodes.

MoP Nanoparticles Supported on Indium-Doped Porous Carbon: Outstanding Catalysts for Highly Efficient CO2 Electroreduction.

Electrochemical reduction of CO2 into value-added product is an interesting area. MoP nanoparticles supported on porous carbon were synthesized using metal-organic frameworks as the carbon precursor, and initial work on CO2 electroreduction using the MoP-based catalyst were carried out. It was discovered that MoP nanoparticles supported on In-doped porous carbon had outstanding performance for CO2 reduction to formic acid. The Faradaic efficiency and current density could reach 96.5 % and 43.8 mA cm-2 , respectively, when using ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate as the supporting electrolyte. The current density is higher than those reported up to date with very high Faradaic efficiency. The MoP nanoparticles and the doped In2 O3 cooperated very well in catalyzing the CO2 electroreduction.

MoP Nanoparticles Supported on Indium‐Doped Porous Carbon: Outstanding Catalysts for Highly Efficient CO2 Electroreduction

AbstractElectrochemical reduction of CO2 into value‐added product is an interesting area. MoP nanoparticles supported on porous carbon were synthesized using metal–organic frameworks as the carbon precursor, and initial work on CO2 electroreduction using the MoP‐based catalyst were carried out. It was discovered that MoP nanoparticles supported on In‐doped porous carbon had outstanding performance for CO2 reduction to formic acid. The Faradaic efficiency and current density could reach 96.5 % and 43.8 mA cm−2, respectively, when using ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate as the supporting electrolyte. The current density is higher than those reported up to date with very high Faradaic efficiency. The MoP nanoparticles and the doped In2O3 cooperated very well in catalyzing the CO2 electroreduction.

Photoluminescence and photocatalytic properties of Er3+-doped In2O3 thin films prepared by sol–gel: application to Rhodamine B degradation under solar light

The effect of Er3+ doping (1%) on the structural, optical and photocatalytic properties of In2O3 thin films deposited on quartz substrates by spin coating was investigated. The In2O3:1% Er3+ films, annealed in the temperature range 800–1000 °C, were characterized by X-ray diffraction, scanning electron microscopy (SEM), atomic force microscopy, UV–Vis spectroscopy, ellipsometry and photoluminescence (PL). The films are polycrystalline with a cubic structure and the lattice parameter increases with the incorporation of Er3+ owing to its larger radius. The SEM images of the film show a granular morphology with large grains (~ 200 nm). The doped In2O3 film exhibits less transparency than In2O3 in the UV–visible region with band gaps of 3.42 and 3.60 eV, respectively. PL shows strong lines at 548 and 567 nm, assigned to Er3+ under direct excitation at 532 nm. The energy diagram of the junction In2O3:1% Er3+/Na2SO4 (0.1 M) solution plotted from physical and photoelectrochemical characterizations shows the feasibility of the films for Rhodamine B (RhB) degradation under solar light. The conduction band at 2.22 V deriving from the In3+:5s orbital is suitably positioned with respect to the O2/O 2 · level (~ 1.40 VSCE), leading to oxidation of 32% of 10 ppm RhB within 40 min of solar irradiation.

Size-Induced Enhancement of Carrier Density, LSPR Quality Factor, and Carrier Mobility in Cr–Sn Doped In2O3 Nanocrystals

Heterovalent dopant ions, such as Sn4+, in In2O3 nanocrystals (NCs) provide free electrons for localized surface plasmon resonance (LSPR). But the same heterovalent dopants act as electron scattering centers, both independently and by forming complexes with interstitial oxygen, thereby increasing LSPR line width. Also, such complexes decrease free carrier density. These detrimental effects diminish the figure-of-merit of LSPR known as the quality factor (Q-factor). Herein, we designed colloidal Cr–Sn codoped In2O3 NCs, where both high carrier density and low carrier scattering can be achieved simultaneously, yielding a high LSPR Q-factor of 7.2, which is a record high number compared to prior reports of doped In2O3 NCs. Q-factors increase systematically from 3.2 for 6.6% Sn doped In2O3 NCs to 7.2 for 23.8% Cr–6.6% Sn codoped In2O3 NCs by increasing the Cr codoping concentration, which is also accompanied by an increase in NC size from 6.7 to 22.1 nm. Detailed characterization and analysis of LSPR spectra ...

Effects of V doping on magnetic and optical properties of oxygen-deficient In2O3 thin films

The scope of the work was to study structural, optical and magnetic behaviors of vanadium (V) doped indium oxide thin films prepared by thermal evaporation. Thin films of vanadium doped oxygen deficient In2O3 were deposited on sapphire, corning glass and Si(100) substrates. EDAX analysis revealed a great reduction in oxygen was happen during evaporation and oxygen deficient undoped and V doped In2O3 thin films were formed. XRD characterization suggested that the present In2O3 portion was in the amorphous state and the observed crystalline peaks were indexed as tetragonal metallic indium. The undoped In2O3 had the lowest transmittance and the transmittance increased with increasing V doping. The optical band gap and refractive index values decreased with increasing V doping. The dependence of magnetization on magnetic field for V doped In2O3 thin films were studied at 300K and 5K. All the samples exhibited soft ferromagnetic behaviour. The parameters of the hysteresis loop were extracted. The achieved results may find usage in magneto-optical applications.

Characterization of Co-existing In2O3-ZnO Nanostructures

In this study, we report the simultaneous growth of both In2O3 and ZnO nanostructures on the same substrate when attempting to achieve heavily Zn-doped In2O3 nanowires with Zn. These oxide structures were synthesized by vapor–liquid–solid growth. Scanning electron microscope imaging and transmission electron microscopy shows the presence of nanostructures with different morphologies while energy-dispersive x-ray and x-ray photoelectron spectroscopy study confirms the elemental structure. Room-temperature photoluminescence (PL) study reveals the presence of oxygen vacancies and surface defects in the structures. Emission related to free and bound excitons as well as the donor–acceptor transitions were observed using temperature-dependent PL. Raman spectroscopy measurement using 442-nm non-resonant excitation sources shows the presence of four phonon modes associated with a cubic In2O3 lattice structure along with the observation of the dominant E 2 high and quasi-longitudinal optical phonon modes associated with wurtzite ZnO. We find that the introduction of high zinc content results in the formation of ZnO nanowires in addition to the In2O3 nanowires, and not the formation of a highly doped In2O3 nanowires.

Effects of Fe-Doping on the Structural and Magnetic Properties of Indium Oxide Nanoparticles Synthesized by Bottom up Techniqu

We study Fe doped In2O3 nanoparticles (NPs) from structural and magnetic point of view. X-ray diffraction (XRD) and transmission electron microscopy (TEM) reveal cubic bixbyite structure for both pure and Fe doped samples thereby confirming successful incorporation of Fe in host In2O3 lattice. Average crystallite size of pure and Fe doped (5% and 10%) In2O3 as calculated by Scherer’s formula shows slight increase from 21 nm for pure to 27 nm for the sample with 10% Fe content. The Williamson Hall (WH) method was also utilized to further determine crystallite size and Fe induced strain in In2O3 lattice. The crystallite sizes by WH plot are found to be 18 nm (for undoped), 22 nm (for 5% Fe) and 24 nm (for 10% Fe). These values are in good agreement with TEM results. Energy dispersive x-ray spectroscopy (EDX) indicates the existence of some oxygen vacancies in Fe doped In2O3 samples. Magnetic measurements show that all Fe doped In2O3 NPs exhibit typical ferromagnetic hysteresis loop with saturation magnetization Ms increasing with increasing Fe concentration. Temperature dependence of field cooled (FC) and zero field cooled (ZFC) magnetizations show no divergence and transition from ferromagnetism to paramagnetism in the temperature range of 5 to 300 K. This evidences a robust room-temperature-ferromagnetism (RTFM) in these NPs. The RTFM of our samples is attributed to the presence of oxygen vacancies in our samples.

Effect of Heat Treatment Under Nitrogen Atmosphere on Sprayed Fluorine Doped In2O3 Thin Films

Fluorine-doped indium oxide thin films (In2O3:F) were prepared at 500°C for different fluorine concentrations (0 at.%, 2 at.%, 6 at.% and 10 at.%) using the chemical spray pyrolysis technique. Structure and surface morphology of these films were characterized by x-ray diffraction (XRD) and atomic force microscopy (AFM). XRD analysis revealed that fluorine doped In2O3 thin films exhibit a centered cubic structure with the (400) preferential orientation. The change of the preferential reflection plane from (222) to (400) was found after doping. The doping optimum concentration of thin film crystal structure is obtained witha fluorine ratio equal to 2 at.%. The crystallinity improvement of In2O3:F (2 at.%) film is detected after annealing at 200°C, 300°C, and 400°C in nitrogen gas for 45 min. Transmission and reflection spectra measurements were performed over the wavelength range of 250–2500 nm. The band gap energy increase from 3.10 eV to 3.45 eV was detected after treatment at 400°C. In parallel, the electrical resistivity, deduced from Hall effect measurements, decreases from 428.90 × 10−4 Ω cm to 6.58 × 10−4 Ω cm.

Optical characterization, absorption and upconversion luminescence in Er3+and Er3+/Yb3+doped In2O3 phosphor

Combustion derived In2O3:Er3+, co-doped with Yb3+phosphor powders have been prepared. Powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and Fourier transform infrared spectroscopy methods are used to characterize the prepared phosphor powders. The intensity parameters (Ωλ, λ=2, 4 and 6), radiative transition probabilities (AR), radiative lifetime (τR) and branching ratios (β) of certain emission transition of Er3+ions for In2O3:Er3+and In2O3:Er3+/Yb3+phosphors have been estimated in the framework of the model given by Judd–Ofelt. Upon excitation at 978nm, upconversion luminescence properties of Er3+and Er3+/Yb3+doped In2O3 phosphors are investigated. The results obtained from optical study confirm the existence of an effective Yb3+to Er3+energy transfer process and it also predict possible mechanisms to populate the 4S3/2 and 4F9/2 levels. The possible upconversion mechanisms are discussed for Er3+and Yb3+ions with energy level diagram.

Electrical and Plasmonic Properties of Ligand-Free Sn(4+) -Doped In2 O3 (ITO) Nanocrystals.

Sn(4+) -doped In2 O3 (ITO) is a benchmark transparent conducting oxide material. We prepared ligand-free but colloidal ITO (8 nm, 10 % Sn(4+) ) nanocrystals (NCs) by using a post-synthesis surface-modification reaction. (CH3 )3 OBF4 removes the native oleylamine ligand from NC surfaces to give ligand-free, positively charged NCs that form a colloidal dispersion in polar solvents. Both oleylamine-capped and ligand-free ITO NCs exhibit intense absorption peaks, due to localized surface plasmon resonance (LSPR) at around λ=1950 nm. Compared with oleylamine-capped NCs, the electrical resistivity of ligand-free ITO NCs is lower by an order of magnitude (≈35 mΩ cm(-1) ). Resistivity over a wide range of temperatures can be consistently described as a composite of metallic ITO grains embedded in an insulating matrix by using a simple equivalent circuit, which provides an insight into the conduction mechanism in these systems.

Reduction of Mn3+ to Mn2+ and near infrared plasmonics from Mn–Sn codoped In2O3 nanocrystals

Isovalent doping in In2O3 using Mn3+ precursor leads to aliovalent Mn2+ doped In2O3 NCs which tune SPR band from near to mid-infrared region.

Structural and morphological studies on Au doped In2O3 thin films by electron beam evaporation technique for solar cell applications

High purity Au and In2O3 powders are taken as starting materials to prepare Au doped In2O3 powder by solid state reaction method. The prepared powders are cold pressed and made into pellets of 1cm diameter and 2 mm thickness, these pellets are sintered at 800°C for 12 hours to make robust targets for electron beam evaporation. The films are deposited on ultrasonically cleaned quartz substrates by electron beam evaporation technique and characterized using stylus profilometer, Grazing Incidence X-ray diffractometer (GIXRD),Energy-dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM). GIXRD results suggest that both the films are polycrystalline in nature with cubic structure having (2 2 2) preferred orientation. The estimated surface roughness from AFM of the films found to increase with Au doping. EDS analysis confirms the stoichiometry of pure and Au doped In2O3 thin films.

Effect of terbium doping on structural, optical and gas sensing properties of In2O3 nanoparticles

In this work, the effect of terbium (Tb3+) as dopant on the structural, optical, electrical and gas sensing properties of In2O3 (indium oxide) nanoparticles has been discussed. In2O3 and Tb3+-doped In2O3 nanoparticles were synthesized by a facile and cost effective co-precipitation method. XRD analysis revealed the formation of bixbyite-type cubic phase for In2O3 and Tb3+-doped In2O3 nanoparticles which was further supported by Raman studies. It was observed that the crystallite size of In2O3 nanoparticles decreased, while structural disorder increased with increase in Tb3+ concentration. SEM micrographs showed that particles were spherical in shape and EDS corroborated the presence of Tb3+ in doped In2O3 nanoparticles. A broadening and shifting of Raman peaks with increase in Tb3+ content was also observed. For gas sensing characteristics, the nanoparticles were applied as thick film onto the alumina substrate and tested at different operating temperatures for various volatile organic compounds (such as methanol, ethanol, acetone) and ammonia. The results indicated that the sensor based on 5%Tb3+-doped In2O3 nanoparticles presented much higher sensor response to 50ppm ethanol at 300°C temperature than the pure In2O3 sensor. The enhancement of the response may be attributed to high surface basicity, small size and large lattice distortion of doped In2O3 sensor.

Nanocasting synthesis of co-doped In2O3: a 3D diluted magnetic semiconductor composed of nanospheres

Mesoporous 3D nanosphere arrays of In2−x Co x O3 (x = 0, 0.01, 0.03, 0.05, and 0.07) were synthesized via nanocasting using the mesoporous silica LP-FDU-12 as a hard template. The mesostructure, morphology, optical properties, and magnetic properties of the materials were determined. The diameter of the nanospheres was about 15–22 nm, and the nanospheres stacked into 0.5–5 μm arrays (particles). The data revealed that the Co ions entered the lattice of the In2O3 bixbyite phase leading to a reduction of the cell parameter. The result also demonstrated that the size of the mesostructured ordering was approximately the same as the particle diameter. Moreover, the optical band gap of Co-doped In2O3 decreased monotonically with the increase of Co concentration and the room-temperature photoluminescence was also observed. The un-doped In2O3 exhibited a ferromagnetic behavior superimposed on a diamagnetic background, while the doped In2O3 displayed a room-temperature ferromagnetic behavior superimposed on a paramagnetic background, which may be correlated with the surface texture of the mesostructure. The mesoporous diluted magnetic semiconductors may find their applications in spintronic nanodevices because of their 3D uniform arrangement of nanospheres and their room-temperature ferromagnetic behavior.

Charge distribution and hyperfine interactions in the vicinity of impurity sites in In2O3 doped with Fe, Co, and Ni

In this paper, first-principles calculations based on density functional theory (DFT) were used to determine TM (TM=Fe, Ni, Co) and Cd impurity locations in the In2O3 host structure, their charge states, the electronic and structural relaxations induced in the host lattice as well as to interpret previous and supplementary experimental results of hyperfine interactions. Different techniques were carried out to characterize TM-doped In2O3 bulk samples prepared by the sol–gel method starting from very pure metals. Perturbed angular correlation (PAC) spectroscopy, a sensitive nuclear technique capable of measuring interactions from electronic charge and spins within an atomic distance, was used to experimentally determine hyperfine interactions at cation sites of In2O3 doped with Co and Ni using In111→Cd111 as probe nuclei. Room temperature results of magnetization measurements in In2O3 doped with Fe, Co and Ni show ferromagnetic ordering coexisting with a paramagnetic behavior for all samples. Results of PAC spectroscopy and DFT calculations show that TM atoms locate as second nearest neighbors of Cd probes preferentially occupy symmetric sites of the doped In2O3 crystal structure with lattice parameters slightly different from that of pure In2O3. Moreover, while a major population of 111Cd probes observes almost the same hyperfine interactions measured for pure In2O3, a small population detects magnetic dipole interactions with magnetic hyperfine field at Cd probes of 2.6T, 3.1T, and 4.6T, respectively for Ni, Co, and Fe doping presenting an almost linear dependence on the number of unpaired 3d electrons of the transition metal impurity.

Gas Sensitivity and Morphologically Characterized of Nanostructure CdO Doped In2O3 Films Deposited by Pulsed Laser Deposition

In this work, films have been grown under various deposition conditions in order to understand the effect of processing on the film properties and to specify the optimum condition, different indium oxide (In2O3) contents (0, 1%, 3%, 5% and 7%) using double frequency pulse laser beam (Q-switching) Neodymium-yttrium aluminum garnet (Nd:YAG (wavelength 532 nm)), to deposit Cadmium Oxide: Indium oxide (CdO:In2O3) films on Aluminum Oxide (sapphire α-Al2O3 (006)) and quartz substrates. The structural properties of samples were investigated by using of surface morphology of the deposits materials has been studied by using atomic force microscopy (AFM). The samples are displayed granular structure. It was found that the grain size decreases with increasing of doping concentration ratio, the smallest grain size equal to (79.11 nm) and (82.99 nm) were achieved at ratio of doping (7%) for quartz and sapphire α-Al2O3 substrate, respectively. The sensitivity of undoped and doped CdO samples toward Nitric dioxide (NO2) gas in air ambient has been measured in the home building system. All samples were tested at mixing ratio (3% NO2:air). The optimal operating temperature is found to be 200-225°C for pure CdO and decreases to 175-200°C for samples. The maximum sensitivity is equal to (263.97%) with response time (13.5 s) and recovery time (15.5 s) are achieved at (3%) doping concentration level for sapphire α-Al2O3 substrate.

Comparative Studies of Rare-Earth Element Y-Doped In2O3 by First-Principles Calculations

In2O3 doped with rare-earth element yttrium shows improved optoelectronic efficiency. Here the structural properties and electronic structures of Y-doped In2O3 are investigated by using a first-principles approximation. For In1.9375 Y0.0625 O3, the d site is the more stable site. The Yi3+ interstitial has a low formation energy and is a possible interstitial defect, which would lead to shallow and abundant donors without sacrificing optical transparency. Since defects are universally distributed in In2 O3 or doped In2 O3, complex defect configurations are also calculated.