Crystalline In2O3 Research Articles

(Invited) High Performance Metal Oxide Thin Film Transistor Using ALD Technology

Field-effect transistors (FETs) based on oxide semiconductors, mainly In2O3 and ZnO, have been commercialized as channel materials for thin-film transistors due to their features such as electron mobility exceeding 10-50 cm2/Vs, extremely low leakage current, and low process temperature. Recently, FETs that can be applied to ferroelectric memory and back end of line have been demonstrated for implementation in ultra-integrated circuits and semiconductor memory. In order to realize various integrated devices using oxide semiconductors, it is necessary to uniformly deposit ultra-thin films of about 5 nm on a three-dimensional structure from the viewpoint of device integration and suppression of short-channel effects. This research group has shown that amorphous In-Ga-O (IGO) is a promising oxide semiconductor material that can be applied to three-dimensional integrated devices. However, it was shown that IGO-FETs have reliability issues because their threshold voltage (Vth) easily fluctuates in response to voltage stress . The purpose of this study was to examine the factors that contribute to Vth instability and to suppress it by evaluating the relationship between FET reliability and IGO composition ratio and annealing temperature, as well as the effect of crystallization. Top-contact/bottom-gate FETs with AlOx protective films were fabricated by depositing 10-11 nm-thick IGO channels on SiO2 (85 nm)/n++-Si substrates using ALD method Triethylindium and Trimethylgallium The composition ratio of In:Ga in the IGO film was controlled by adjusting the ratio of growth cycles of the InOx and GaOx layers. positive bias stress (PBS), in which a positive voltage is applied to the gate electrode. The reliability of amorphous IGO against PBS was found to depend on the composition ratio of In:Ga and annealing temperature. It is known that the formation energy of O-O bonds corresponding to excess oxygen is lower in amorphous oxide semiconductors than in single-crystal and polycrystal structures due to their higher structural degrees of freedom. It was experimentally clarified that electron capture occurs more easily in IGO systems than in other oxide semiconductors (Ex. In-Zn-O), which is consistent with theoretical calculations in previous studies. In addition, we focused on crystalline Ga-doped In2O3 to improve the reliability of the IGO system and developed a deposition process using ALD method. We demonstrated that FETs with polycrystalline IGOs as channels have superior mobility and reliability compared to amorphous IGOs. The present study clarified that excess oxygen must be reduced during deposition of oxide semiconductors using the ALD method, and that polycrystalline oxide semiconductors are effective in improving reliability.

Saturation Mobility of 100 cm2 V-1 s-1 in ZnO Thin-Film Transistors through Quantum Confinement by a Nanoscale In2O3 Interlayer Using Spray Pyrolysis.

In this study, we present a comprehensive study on the fabrication and characterization of heterojunction In2O3/ZnO thin-film transistors (TFTs) aimed at exploiting the quantum confinement effect to enhance device performance. By systematically optimizing the thickness of the crystalline In2O3 (c-In2O3) layer to create a narrow quantum well, we observed a significant increase in saturation mobility (μSAT) from 12.76 to 97.37 cm2 V-1 s-1. This enhancement, attributed to quantum confinement, was achieved through the deposition of a 3 nm c-In2O3 semiconductor via spray pyrolysis. Various In2O3 layer thicknesses (2-5 nm) were obtained by adjusting precursor solution concentration, flow rate, and number of spray cycles. Post annealing treatments were employed to reduce the defects at the interface and within the oxide film, enhancing device stability and performance. Transmission electron microscopy (TEM) confirmed the uniformity of the c-In2O3 film thickness, while variations in thickness significantly influenced TFT performance, particularly the turn-on voltage (VGS) due to changes in the carrier concentration. Ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) supported the formation of a potential well with a two-dimensional electron gas (2DEG). The study of single and multiple superlattice structures of consecutive c-In2O3 and c-ZnO layers provided insights into the effects of multiple quantum wells on the TFT performance. This research presents an advanced approach to TFT optimization, highlighting high reliability, and environmental and bias stabilities. These lead to enhanced mobility and performance uniformity through the precise control of c-In2O3 layer thickness for the quantum confinement effect.

Exploring Heterointerface Characteristics and Charge-Storage Dynamics in ALD-Developed Ultra-Thin TiO2-In2O3/Au Heterojunctions

Directional ionic migration in ultra-thin metal-oxide semiconductors under applied electric fields is a key mechanism for developing various electronic nanodevices. However, understanding charge transfer dynamics is challenging due to rapid ionic migration and uncontrolled charge transfer, which can reduce the functionality of microelectronic devices. This research investigates the supercapacitive-coupled memristive characteristics of ultra-thin heterostructured metal-oxide semiconductor films at TiO2-In2O3/Au Schottky junctions. Using atomic layer deposition (ALD), we nano-engineered In2O3/Au-based metal/semiconductor heterointerfaces. TEM studies followed by XPS elemental analysis revealed the chemical and structural characteristics of the heterointerfaces. Subsequent AFM studies of the hybrid heterointerfaces demonstrated supercapacitor-like behavior in nanometer-thick TiO2-In2O3/Au junctions, resembling ultra-thin supercapacitors, pseudocapacitors, and nanobatteries. The highest specific capacitance of 2.6 × 104 F.g−1 was measured in the TiO2-In2O3/Au junctions with an amorphous In2O3 electron gate. Additionally, we examined the impact of crystallization, finding that thermal annealing led to the formation of crystalline In2O3 films with higher oxygen vacancy content at TiO2-In2O3 heterointerfaces. This crystallization process resulted in the evolution of non-zero I-V hysteresis loops into zero I-V hysteresis loops with supercapacitive-coupled memristive characteristics. This research provides a platform for understanding and designing adjustable ultra-thin Schottky junctions with versatile electronic properties.

Remarkable Bias‐Stress Stability of Ultrathin Atomic‐Layer‐Deposited Indium Oxide Thin‐Film Transistors Enabled by Plasma Fluorination

AbstractA low‐thermal‐budget fabrication approach is developed to realize high‐performance fluorine‐doped indium oxide (In2O3:F) thin‐film transistors (TFTs) with remarkable bias‐stress stability. The ultrathin transistor channel layer is prepared by a re‐developed atomic layer deposition (ALD) process of using cyclopentadienyl indium(I) (InCp) and O2 plasma to deposit a crystalline In2O3 film, followed by a new fluorine doping strategy to use CF4 plasma to afford the In2O3:F layer. As revealed by the density functional theory (DFT) analysis, the fluorine doping can stabilize the lattice oxygen and electrically passivate the problematic VO defects in In2O3 by forming the FOFi spectator defects. Therefore, the fabricated In2O3:F TFTs show simultaneously excellent electrical performance and remarkable bias‐stress stability, with high µFE of 35.9 cm2 V−1 s−1, positive Vth of 0.36 V, steep SS of 94.3 mV dec−1, small hysteresis of 33 mV, and small ΔVth of −111 and 49 mV under NBS and PBS, respectively. This work demonstrates the high promise of the fluorinated ALD In2O3:F TFTs for the CMOS back‐end‐of‐line (BEOL) compatible technologies toward advanced monolithic 3D integration.

Photoreduction of CO2 on Pd-In2O3: Synergistic optimization of progressive electron transfer via amorphous/crystalline Pd and oxygen vacancies

The progressive transfer of photogenerated electrons between the catalyst components and reactants is of great significance for photocatalysis. Amorphous Pd (PdA) and oxygen vacancies (VOs) were simultaneously introduced in Pd-In2O3 exploiting hydrogen-induced amorphization effects; 0.6 wt% Pd-In2O3 exhibited a 4.5-fold increase in activity and a 3.2-fold higher selectivity toward CH3OH + CO (63.62 %) compared with In2O3. Multiple in situ techniques and theoretical calculations revealed that intercomponent electron transfer channels were established via various interface structures formed between PdA or crystalline Pd (PdC) and In2O3; PdA acted as electronic pump, facilitating the transfer and separation of photogenerated electrons, resulting in their subsequent enrichment on the surface of PdA. Simultaneously, PdA acted as electron-donating adsorption site for H2O, increasing the number of electrons received by H2O, further inhibiting the competitive adsorption of H2O and CO2 on VO sites, and promoting the hydrogen evolution reaction. Additionally, the electronic coupling between PdC and VOs could significantly decrease the electron-donating ability of VOs, reducing the number of electrons received by CO2, thus effectively regulating the degree of CO2 reduction. This study employs PdA/PdC and VOs to synergistic optimize the progressive transfer of photogenerated electrons, and presents a novel approach for elucidating the catalytic mechanism.

Characteristics of Ultrathin Indium Oxide Thin‐Film Transistors with Diverse Channel Lengths Fabricated by Atomic Layer Deposition

The oxide thin‐film transistors (TFTs) with ultrathin (5 nm) crystalline In2O3 channels formed by an atomic layer deposition method are fabricated. The ultrathin In2O3 films are formed at a deposition temperature of 300 °C using (3‐(dimethylamino)propyl)dimethylindium as the indium precursor and ozone as the oxidizing agent. The postannealing is performed in an oxygen atmosphere for 2 h at 300 °C. The scaling behavior of the field‐effect mobility (μFE) is investigated as a function of the channel length (Lch). As Lch increases from 5 to 160 μm, the average μFE is measured and found to increase from 20.2 to 33.6 cm2 V−1 s−1. It shows the average device properties of subthreshold swing of 0.32 V dec−1, turn‐on voltage of −5.5 V, and on/off current ratio of 107. To understand this trend, the transmission line model is utilized to extract the resistance components present across the channel quantitatively. The analyses reveal that among the components comprising the total resistance, the fraction of Rc increases as Lch becomes shorter. Thus, Rc emerges as a dominant parameter that determines μFE. In this regard, the results have technical significance in vertical TFTs and high‐resolution applications in which predictable scaling matters.

Tandem catalysts of different crystalline In2O3/sheet HZSM-5 zeolite for CO2 hydrogenation to aromatics

In tandem catalysts, not only good synergy between the two active components is required, but also the precise control of the spatial distribution between the two active components of metal oxides and zeolite is crucial for the migration and conversion of reaction intermediates in the direct conversion of CO2 to hydrocarbons. The correlation between the metal and the acidic site of zeolite has traditionally been simplified as “the closer, the better”. However, it should be noted that this principle only holds true for a portion of tandem catalysts. Therefore, this paper studied the effect of different crystalline In2O3 (cubic phase, hexagonal phase, and mixed cubic/hexagonal phase) and sheet HZSM-5 zeolite tandem catalysts on the activity of CO2 hydrogenation reaction under different spatial distribution. The generalized gradient approximation (GGA) of density functional theory (DFT) were used to simulate the adsorption energy of CO2 by oxygen vacancy on c-In2O3(111) and h-In2O3(104) planes, it was found that Ov1 on c-In2O3(111) and Ov4 on h-In2O3(104) had the strongest adsorption energy for CO2. In addition, it has been observed that the proximity of the two active components (e.g., during mortar mixing) results in decreased catalytic performance. This is due to the migration of metal In, which neutralizes the acid sites of zeolites and leads to inefficient conversion of methanol reaction intermediates to aromatics. As a result, CO2 conversion and aromatic selectivity are decreased.

Precursor decomposition mechanism of In2O3 powder for oxide ceramic targets

In this study, precursor decomposition as well as nucleation and growth processes during the preparation of In2O3 powders via chemical precipitation were investigated. This is to provide guidance for the preparation of high-quality In-based oxide target powders. In-situ phase and microstructure evolution during thermal decomposition of precursors were analyzed. In addition, decomposition behavior of precursors at different heating rates was explored. Results show that amorphous In(OH)3 precursor powder gradually decomposes and transforms into crystalline In2O3 powder during heating process. Its degree of crystallinity increases with the increase in temperature. Fine and homogeneous In2O3 powder with average grain size of 54.46 nm was obtained by holding the powder at 770 °C for 3 h. The decomposition of precursors at any given heating rate can be divided into two stages: (i) dehydration and (ii) nucleation and crystallization. However, higher heating rate clearly results in temperature hysteresis effect, the occurrence of decomposition reaction at higher temperature, and an increase in the maximum reaction rate of decomposition reaction. Moreover, activation energy of thermal decomposition was obtained using model-free transformation method. Decomposition reaction model of In(OH)3 precursor was established using model-fitting method. It was deduced that first-stage reaction mechanism is three-dimensional diffusion. Reaction rate in this stage is controlled by product layer diffusion. Furthermore, second-stage reaction mechanism is random nucleation and subsequent growth. Reaction rate in this stage is controlled by nucleation and growth rates.

Ultrasensitive sensing performances of amphiphilic block copolymer induced gyrus-like In2O3 thick films to low-concentration acetone.

In the present work, an inducible assembly of di-block polymer compounds approach was employed for the synthesis of mesoscopic gyrus-like In2O3 by using lab-made high-molecular-weight amphiphilic di-block copolymer poly(ethylene oxide)-b-polystyrene (PEO-b-PS) as a revulsive, with indium chloride as an indium source and THF/ethanol as the solvent. The obtained mesoscopic gyrus-like In2O3 indium oxide materials exhibit a large surface area and a highly crystalline In2O3 nanostructure framework, and the gyrus distance is about 40 nm, which can facilitate the diffusion and transport of acetone vapor molecules. By using this material as a chemoresistance sensor, the obtained gyrus-like indium oxides were used as sensing materials, showing an excellent performance to acetone at a low operating temperature (150 °C) due to their high porosity and unique crystalline framework. The limit of detection of the thick-film sensor based on indium oxides is appropriate for diabetes exhaled breath acetone concentration detection. Moreover, the thick-film sensor shows a very fast response-recovery dynamics upon contacting acetone vapor due to its abundant open folds mesoscopic structure, and also to the large surface area of the nanocrystalline gyrus-like In2O3.

Rapid and Green Electric-Explosion Preparation of Spherical Indium Nanocrystals with Abundant Metal Defects for Highly-Selective CO2 Electroreduction

Electrochemical conversion of CO2 into high-value-added chemicals has been considered a promising route to achieve carbon neutrality and mitigate the global greenhouse effect. However, the lack of highly efficient electrocatalysts has limited its practical application. Herein, we propose an ultrafast and green electric explosion method to batch-scale prepare spherical indium (In) nanocrystals (NCs) with abundant metal defects toward high selective electrocatalytic CO2 reduction (CO2RR) to HCOOH. During the electric explosion synthesis process, the Ar atmosphere plays a significant role in forming the spherical In NCs with abundant metal defects instead of highly crystalline In2O3 NCs formed under an air atmosphere. Analysis results reveal that the In NCs possess ultrafast catalytic kinetics and reduced onset potential, which is ascribed to the formation of rich metal defects serving as effective catalytic sites for converting CO2 into HCOOH. This work provides a feasible strategy to massively produce efficient In-based electrocatalysts for electrocatalytic CO2-to-formate conversion.

Texture in ITO films deposited at oblique incidence by ion beam sputtering

Texture of crystalline In2O3:Sn (ITO) thin films prepared by combining ion beam sputtering (IBS) at room temperature and oblique angle deposition (OAD) has been studied depending on the vapor incidence on Si substrates (α, ranging from 50°to 85°) and the ions used to sputter the target (argon or xenon accelerated at 1.2keV). Films obtained using Xe ions show an unusual evolution depending on the deposition angle α, with the development of a dual biaxial (111) off-axis texture for α≤70°, and a switching in the preferred out-of-plane orientation from [111] to [001] for α>70°that leads to a biaxial (001) texture at highest deposition angles. These behaviors are well described by mechanisms involving a maximization of the direct capture of the adatoms on {111} planes, which can however be hindered when mobilities are exalted such as in the case of Ar deposition. The tuning of adatoms mobilities through the IBS process mixed with the control of the deposition angle offered by the OAD geometry appears as an efficient route to achieve an upgraded texture engineering in nanostructured ITO thin films.

Sequential Infiltration Synthesis of Nano-porous and Electrically Conductive In2O3 for Water Remediation

Sequential infiltration synthesis (SIS) is derivative of atomic layer deposition (ALD) that expands the morphological palate of materials to enable an even greater variety of applications. During SIS, a vapor phase precursor reversibly and selectively adducts with a polymer matrix. By controlling the polymer moieties, precursor chemistry, and reaction parameters such as time, temperature, and pressure, the process can yield precise deposition and high growth rates (equivalent to > 30 nm/cycle) in complex matrices that are 100s of nanometers thick. In our work, we leverage those parameters to deposit nano-porous In2O3 electrodes for water remediation. Electrified water treatment has the potential to greatly improve energy and cost efficiency over current methods. SIS has been used previously to create well-defined nano-porous structures, yet there has not been a report of an electrode developed via SIS. Our work describes how amorphous InOHx clusters deposited by SIS combine to form an interconnected and electrically conductive network of crystalline In2O3. Changes in optical parameters, probed by spectroscopic ellipsometry, reveal that the oxygen annealing burns off the polymer and leads to partial densification of the film. XRD and TEM further demonstrate the development of a crystalline network of In2O3 with grain sizes of approximately 20 nm. Additional annealing in forming gas yields resistivity values on the order of 10-3 Ω*m. Aside from the annealing conditions, the microstructure of the In2O3 network also influences electrical properties. Using SIS to control the volume fraction of In2O3 in PMMA, annealed samples were prepared with porosity ranging from 30-80% In2O3. As the amount of In2O3 increases, Hall measurements reveal that the resistivity decreases and the mobility increases, which suggests that the prevalence of charge conduction pathways within the In2O3 film can be controlled. We demonstrate nano-porous In2O3 films with tunable electrical properties and further highlight the opportunity to precisely control properties of In2O3 for applications such as water remediation.

Solvent and catalyst-free synthesis of In2O3 octahedron using single-step thermal decomposition technique for NO2 detection

In this article, a highly crystalline In2O3 octahedron has been synthesized by a single-step solvent and catalyst-free thermal decomposition method. The as-synthesized sample has been characterized using XRD, FESEM, HR-TEM, and XPS. The characterization results confirmed the formation of the cubic phase of the In2O3 sample with the octahedron morphology. The gas sensing characteristics of the In2O3 octahedron sample for oxidizing and reducing gases have been investigated systematically. The optimum operating conditions for selective detection of chemical inputs have been determined. Additionally, a maximum sensor response (~4252%) along with fast response (recovery) times ~30 s (13 s) has been obtained for NO2 gas (30 ppm) at its operating temperature 200 °C. The results suggested that the In2O3 octahedron sensor proposes a promising candidate for NO2 detection at its optimum operating temperature of 200 °C and can open up new ways to integrate these sensors with future electronic devices.

Novel photoluminescent In2O3/a-SiC core/shell nanostructure synthesized by HW-assisted PECVD method

Semiconductor core/shell nanostructures have been recently attracted a great interest due to interesting properties and wide potential applications. In this work, In2O3/a-SiC core/shell nanostructure was successfully synthesized for the first time using hot wire-assisted plasma-enhanced chemical vapor deposition technique. The crystalline structure, morphology, chemical composition, and optical properties of the deposited film were investigated by variety of characterization techniques including X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, UV–Vis–NIR spectrophotometry, photoluminescence spectroscopy (PL) and Raman scattering spectroscopy. The results verified the formation of core/shell nanostructures, crystalline In2O3 as a core and amorphous SiC as a shell, successfully. The average diameter and thickness of synthesized core and shell were 101 and 38 nm, respectively. A strong and broad room-temperature PL emission in the visible and near-infrared region was observed for the synthesized structure as a result of synergic effects. This broad band was consisted of Gaussian peaks at the wavelengths of 570, 656, 728, 763, and 842 nm. The origin of different PL peaks was discussed in the paper. The results show that the novel In2O3/a-SiC core/shell nanostructure is a good candidate for optical applications.

Black indium oxide a photothermal CO2 hydrogenation catalyst

Nanostructured forms of stoichiometric In2O3 are proving to be efficacious catalysts for the gas-phase hydrogenation of CO2. These conversions can be facilitated using either heat or light; however, until now, the limited optical absorption intensity evidenced by the pale-yellow color of In2O3 has prevented the use of both together. To take advantage of the heat and light content of solar energy, it would be advantageous to make indium oxide black. Herein, we present a synthetic route to tune the color of In2O3 to pitch black by controlling its degree of non-stoichiometry. Black indium oxide comprises amorphous non-stoichiometric domains of In2O3-x on a core of crystalline stoichiometric In2O3, and has 100% selectivity towards the hydrogenation of CO2 to CO with a turnover frequency of 2.44 s−1.

Unveiling in situ evolved In/In2O3−x heterostructure as the active phase of In2O3 toward efficient electroreduction of CO2 to formate

Uncovering the structure evolution and real active species of energy catalytic materials under reaction conditions is important for both understanding structure–activity relationship and constructing electrocatalysts for CO2 electroreduction (CO2ER). And integrating CO2ER with an anodic organic transformation to replace the oxygen evolution reaction is highly desirable. Here, In2O3 is selected as the model material to reveal the surface reconstruction under CO2ER condition. In situ and ex situ results reveal that the electrochemical in situ reconstruction of crystalline In2O3 leads to the formation of crystalline-In/amorphous-In2O3−x heterostructure (In/In2O3−x). In/In2O3−x acts as the real active phase with Faradaic efficiency of ~ 89.2% for the formate, outperforming In (~67.5%). The improved performance can be ascribed to electron-rich In rectified by Schottky effect of In/In2O3−x heterostructure. Impressively, formate and high-value octanenitrile can be simultaneously achieved by integrating CO2ER with octylamine oxidation in an In/In2O3−x‖Ni2P two-electrode electrolyzer.

Dual-gate crystalline oxide-nanowire field-effect transistors utilizing ion-gel gate dielectric

Dual-gate structure field-effect transistors (DG FETs) can provide various advantages such as high output current, enhanced mobility, and tunability of threshold voltage (VTH) by adversely controlling the two channels formed at both top and bottom gate dielectric interfaces. Here, we present high-mobility DG structure FETs using crystalline Ga-doped In2O3 (IGO) nanowires (NWs) as channel and high-k ion-gel as a top gate dielectric layer. To enhance the electrical properties of IGO NW FETs such as field-effect mobility, on/off ratio, VTH, and subthreshold slope, optimization of electrospinning, Ga doping in In2O3 NWs, and thermal annealing was carried out. The optimized IGO NW FETs with a single SiO2 gate dielectric exhibited field-effect mobility of ~6.0 cm2/(V·s), on/off ratio of >107, subthreshold slope of 0.73 V/decade, and VTH of ~0 V. Also, the IGO NW FETs showed excellent operation stabilities under positive-gate-bias and negative-bias-illumination stress conditions. Furthermore, by using a high-k ion-gel film as the second gate dielectric layer, DG IGO NW FETs with field-effect mobility up to ~35.1 cm2/(V·s) were realized which is comparably higher than those of single-gated IGO NW FETs (6.0–6.5 cm2/(V·s)).

Enhanced gas sensing performance based on p-NiS/n-In2O3 heterojunction nanocomposites

Heterostructured semiconductor materials, combining the collective advantages of individuals and synergistic properties, have spurred great interest as a new paradigm toward detecting of volatile organic compounds recently. Direct use of NiS as a sensing material is impractical because the structure of NiS is unstable, exhibiting an undesirable sensing performance. Herein, we firstly report its incorporation into an ethanol gas sensor with a conventional n-type sensitive material of In2O3, and the gas sensing performance of the NiS@In2O3 nanocomposites has been significantly enhanced. Nanofiber-like NiS and In2O3 were fabricated via a synergetic approach of electrospinning and calcination processes. The diameters of crystalline NiS and In2O3 are about 150 nm and 120 nm, respectively. Then, the NiS@In2O3 nanocomposites were prepared via re-calcination of as-prepared NiS and In2O3 nanofibers. The results show that the sensor based on NiS@In2O3 exhibits a detecting limit of as low as 5 ppm and a short response time of 8 s at the optimum temperature of 300 ºC, which outstripped that (13 s) of pristine In2O3 and pure NiS sensors (21 s) for the detection of ethanol gas. The remarkable improvement of sensing performance can be attributed to the p-n heterojunction in multi-component phases of NiS and In2O3.

Properties of Au incorporated In2O3 films

Effect of gold loading on the structural, morphological, optical and electrical properties of RF magnetron sputtered In2O3 films is discussed. Annealing is done to analyse the properties of heavily Au loaded In2O3 film after thermal treatment. Au acts as a nucleation centre and improves the crystalline quality of cubic bixbyite In2O3 films with moderate Au loading concentration. FESEM and AFM images of the as-deposited films present smooth surface morphology with a dense distribution of small grains. Random distribution of Au nanorods can be seen in the FESEM image of the 10 wt% Au incorporated film annealed at a temperature of 400 °C. The present study reveals the formation of smooth, crack-free, crystalline In2O3 films with Au incorporation. XPS analysis suggests the predominance of metallic state of Au in the Au loaded films. Absorption studies show an enhanced absorption in both as-deposited and annealed Au loaded films. Transmittance of In2O3 films is considerably modified but electrical properties are not much modified by Au incorporation. Enhancement in UV luminescence emission of In2O3 films ~378 nm is observed with Au incorporation up to 3 wt%. Intense UV emission in Au incorporated films opens a possibility of using these films for UV light emission applications.

Transparent Amorphous Oxide Semiconductor as Excellent Thermoelectric Materials

It is demonstrated that transparent amorphous oxide semiconductors (TAOS) can be excellent thermoelectric (TE) materials, since their thermal conductivity (κ) through a randomly disordered structure is quite low, while their electrical conductivity and carrier mobility (μ) are high, compared to crystalline semiconductors through the first-principles calculations and the various measurements for the amorphous In−Zn−O (a-IZO) thin film. The calculated phonon dispersion in a-IZO shows non-linear phonon instability, which can prevent the transport of phonon. The a-IZO was estimated to have poor κ and high electrical conductivity compared to crystalline In2O3:Sn (c-ITO). These properties show that the TAOS can be an excellent thin-film transparent TE material. It is suggested that the TAOS can be employed to mitigate the heating problem in transparent display devices.