Indium Target Research Articles

Advances in Room Temperature of Indium Aluminum Nitride InAlN Deposition via Direct Current (DC) Co-Sputtering for Solar Energy Applications

This study presents an innovative method for the synthesis of indium aluminum nitride (InAlN) layers by direct current (DC) co-sputtering at room temperature, with the aim of reducing production costs of optoelectronic devices. Indium and aluminum targets are used, varying the power applied to the aluminum target. The results show that increasing the target power favors the formation of aluminum nitride (AlN), which modifies the chemical composition of the material. The layers obtained present smooth surfaces with a roughness of less than 3 nm, which is beneficial for applications requiring interfaces with low defect density. Regarding the optical properties, it is observed that the optical bandgap varies between 1.8 eV and 2.0 eV, increasing with the target power. Hall effect measurements indicate a decrease in the free carrier concentration and an increase in the resistivity with increasing power. This approach allows for the synthesis of InAlN with properties suitable for optoelectronic applications, solar cells, photocatalysis, and photoelectrocatalysis at low cost.

Structural, optical and electrical properties of ZnO–InN quaternary compound films

The ZnO–InN compound films were fabricated via both RF and DC sputtering by using indium and zinc metal target, where N2O and N2 gases were employed as the sputtering gas. The optical band gap was continuously tuned from 1.9 to 3.4 eV by precisely tailoring the chemical composition of the compound film. Both optical band gap and lattice spacing can be described by Vegard rule well. The carrier density can be adjusted up to 6.20 × 1020 cm−3 by varying the chemical composition of ZnO–InN compound. When the carrier density exceeds ∼1020 cm−3, the ZnO–InN compound films show the characteristics of degenerated semiconductor. Our experiments also reveal that the grain boundary scattering dominates carrier transport for ZnO–InN compound films with carrier density below 1020 cm−3.

High-quality transparent conductive indium oxide film deposition by reactive pulsed magnetron sputtering: Determining the limits of substrate heating

A transparent conductive oxide (TCO) should have a combination of high electrical conductivity and optical transmission property to fulfill the challenging demands of industrial applications. So far, doped TCOs have been mostly considered to fulfill the technological challenges. In this study, we demonstrate that indium oxide (In2O3) thin films without intentional doping can be deposited with high crystallinity under specific film growth conditions leading to thin films with high mobility, high electrical conductivity, and high transmittance. In2O3 thin films have been deposited by reactive pulsed direct current magnetron sputtering (pulsed DCMS) from an indium target on substrates in a temperature range from room temperature (RT) to 600 °C. Detailed investigations on In2O3 thin films are performed and the film properties such as crystallinity, microstructure, chemical bonding states, electrical and optical properties are revealed. Enhanced plasma density and ionization degree provided by the employed reactive pulsed DCMS and the intentional substrate heating during the thin film deposition give possibility to deposit highly crystalline thin films which are preferentially oriented in (222) direction. The substrate heating enhances the crystallinity of the grown films up to a certain optimum temperature: 400 °C. When the substrate temperature is above 400 °C, the carrier concentration and mobility decrease due to the grain refinement effect caused by growth competition of grains in different orientations. The films grown at 400 °C indicate the presence of high oxygen vacancy concentrations, which can directly be associated with a high charge carrier concentration despite the lack of intentional doping. The undoped In2O3 films in this study grown at 400 °C show highly promising and competitive electrical properties such as low resistivity of 1.28 × 10-4 Ω⋅cm and the high carrier mobility of 69 cm2/Vs. The average transmittance of the In2O3 films with the highest conductivity is found to be greater than 80% in the visible to the near-infrared spectral region owing to an enhancement in the carrier mobility and an optical bandgap in the range from 3.61 eV to 3.77 eV.

Analysis and evaluation of liquid metal anode target material of transmission X-ray tube

In recent years, due to the fluidity and thermal conductivity of the liquid metal, the use of liquid metal as an anode target is one of the ways to improve the brightness of X-ray tubes. In this paper, the optimal thickness and conversion efficiency of three kinds of target materials under different energies were discussed by the Monte Carlo method. The optimal thickness of the gallium target is 6.2 μm when the incident electron beam energy is 50 keV and the optimal thickness of the indium target and the tin target was 4 μm. The X-ray conversion efficiency of the gallium target was 44.28% higher than that of the silver target as well as the ratio of X-ray count with the K lines to total count was 53.38%. The gallium target is suitable to be the material of a liquid metal anode target of transmission X-ray tube within the concerned energy range.

Work Function Extraction of Transparent Conducting Indium Oxide Films Used As Gate Electrode for MOSFET

Indium Oxide (In2O3) has received a great deal of attention recently as a transparent conducting oxide (TCO) semiconductor that finds applications in photovoltaic solar cells, transparent windows [1] and flat panel displays due to its high electrical conductivity and good optical transparency in the visible region [2]. It is critical to understand the work function (WF) of a material since it is an important characteristic which has an impact on the device performance.In this work, WF of In2O3 has been estimated by fabricating n-Metal Oxide Semiconductor Field Effect Transistor (NMOSFET). Fabrication of two MOSFET devices has been carried out using four-level mask. The source and drain contacts for both the devices have been prepared by using Aluminum metal. The gate contact for one of the MOSFET devices was prepared using Aluminum metal and transparent conducting In2O3 is used as the gate contact for the second MOSFET. Aluminum deposition was carried out using thermal evaporation technique. A 2-inch copper-backed indium target is used to deposit thin films of In2O3 by RF magnetron sputtering and varying the oxygen gas flow. The substrate temperature is held constant at room temperature. Electrical characterization is performed on the fabricated MOSFETs which is further used in extracting the WF of In2O3 thin films. Timo Jäger, Yaroslav E. Romanyuk, Shiro Nishiwaki, Benjamin Bissig, Fabian Pianezzi, Peter Fuchs, Christina Gretener, Max Döbeli, and Ayodhya N. Tiwari , "Hydrogenated indium oxide window layers for high-efficiency Cu(In,Ga)Se2 solar cells" , Journal of Applied Physics 117, 205301 (2015)Min-Suk Lee, Won Chel Choi, Eun Kyu Kim, Chun Keun Kim, Suk-Ki Min, Characterization of the oxidized indium thin films with thermal oxidation, Thin Solid Films, Volume 279, Issues 1–2, 1996, Pages 1-3, ISSN 0040-6090.

Electrical and Optical Studies of Reactively Sputtered Indium Oxide Thin Films

Electrical and optical properties of transparent conducting Indium Oxide (In2O3) thin films were studied. These films were deposited by reactive RF sputtering process using Indium target in the presence of oxygen as reactive gas with argon. The pressure and the oxygen gas flow ratios during sputtering were varied to investigate their effect on the resistivity, optical transmission, refractive index, and optical bandgap of In2O3 thin films. The lowest reported resistivity in this study is 2 × 10−3 Ω-cm. The optical transmission was more than 80% in the wavelength range of 400 nm to 800 nm. The optical study revealed the wide optical bandgap of 3.712 eV and 3.875 eV of the deposited In2O3 films. The films showed refractive indices in the range of 1.99 to 2.22. The elemental composition of In2O3 films has been studied through X-ray Photoelectron Spectroscopy (XPS).

Investigation of Electrical and Optical Properties of Low Resistivity Indium Oxide Thin Films

Indium oxide (In2O3) films were deposited by reactive sputtering using an indium target in the presence of oxygen and argon as sputtering gases. The electrical and optical properties of In2O3 films specifically sheet resistance, resistivity, optical transparency, refractive index, and optical bandgap were investigated as a function of oxygen gas flow ratio, keeping the substrate at room temperature. The lowest reported resistivity in this study is 2 x 10-3 Ω-cm. The optical transmission was more than 80% in the wavelengths of 400 nm to 800 nm. The optical study revealed the wide optical bandgap of 3.875 eV of the deposited In2O3 films. The films showed refractive indices in the range of 1.99 to 2.22. The elemental composition of In2O3 films has been studied through X-ray Photoelectron Spectroscopy (XPS).

Production and Monitoring of Neutron Flux by Activation Detectors

The neutron generation technique was tested on the microtron M-10 with an output electron beam of 8.7 MeV. Given the low energy that the microtron can provide to electrons, the bremsstrahlung induced photonuclear reaction 9Be (γ, n), which has a low threshold, was chosen for neutron generation. Cobalt and indium targets were tested as activation detectors to estimate the neutron flux density. In the cobalt target, the isomeric state of 60mCo with an energy of 58.6 keV and a half-life of 10.5 minutes is well activated. Two well-known additional gamma lines of standard cobalt source permit to clarify the absolute value of the neutron flux. The activated indium target has four gamma lines bound to the 116mIn isomer β- decaying with the half-life of 54.4 minutes, what is convenient for measurement of gamma spectrum. Despite the low energy of the output electron beam, at a beam intensity of 5 μA it is possible to obtain an almost isotropic neutron flux of 107 n/(s∙cm2).

Reactive Sputtering Growth of Indium Nitride Thin Films on Flexible Substrate Under Different Substrate Temperatures

Indium nitride (InN) thin films were deposited on kapton polyimide substrate by using reactive gas-timing radio frequency (RF) sputtering technique. An indium target with purity of 99.999% was used. Throughout this work, the RF power and gas ratio of argon and nitrogen were maintained at 60 W and 40:60 (Ar:N2), respectively. The substrate temperature was varied from room temperature to 300°C. The surface morphology, structural and electrical properties of the deposited thin films as a function of the substrate temperature were investigated. All the deposited InN thin films have wurtzite crystal structure with preferred orientation along the (101) direction. The InN (101) peak becomes stronger and sharper as the substrate temperature increases from 100°C to 300°C. In addition, the packing density of the grains increases as the substrate temperature increases. The deposited InN films exhibit n-type conductivity behavior and its Hall mobility increases from 720 cm2/V-s to 2670 cm2/V-s as the substrate temperature increases from room temperature to 300 °C. These results imply that nucleation and crystal growth as well as the crystalline quality were improved at higher substrate temperatures. All the results lead to conclude that the optimal substrate temperature for the deposition of InN was 300 °C.

Formation, aging and self-assembly of regular nanostructures from laser ablation of indium and zinc in water

In this paper, we study the effects of pulse duration, ablation energy and liquid temperature on the formation, aging and self-assembly of nanoparticles during pulsed laser ablation. This report proves for the first time that indium hydroxide can be obtained by pulsed laser ablation of indium target in liquid, and regular nanostructures will be formed after aging and self-assembly processes. In the ablation process of zinc target, zinc and zinc oxide will be produced simultaneously, and zinc oxide is the inevitable result of aging. Compared with longer pulses, nanoparticles obtained by ultra-short pulses have smaller size, narrower size distribution and more stable structure.

Comparative Study of Gas Ratio on Indium Nitride Thin Films Grown on Flexible Substrates Prepared by Reactive Sputtering Method

In this report, indium nitride (InN) thin films were deposited on kapton polyimide flexible substrate by reactive radio frequency (RF) sputtering method using an indium target in a mixture of Ar and N2gases. The effects of the Ar:N2gas ratio on the properties of the deposited InN thin films were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and energy dispersive (EDX) spectroscopy. The XRD revealed that the deposited films composed of polycrystalline wurtzite InN. The FESEM and AFM surface morphologies showed smooth and uniform surface of gas ratio at 60:40 compare to others gas ratio. Overall, the characteristics of the InN thin films were effectively improved with combination the N2:Ar gas ration at 60:40. The results showed that the gas ratio plays an important role in improving the properties of the InN thin films.

Indium Nitride Nanoparticles Prepared by Laser Ablation in Liquid

Indium nitride InN nanoparticles NPs suspension prepared by Nd:YAG laser ablation of indium target submerged under ammonium hydroxide. The Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, UV/VIS/NIR spectrophotometer and Conductivity meter were used to determine the properties of the nanoparticles prepared with different laser conditions. Fourier transform infrared spectra exhibit the presence of In[Formula: see text]N and In–N bonds, which indicates the formation of InN particles. X-ray diffraction pattern observed in the formation of InN NPs with cubic phase, the average diameters of the dominant peak c-InN (101) were approximately 2[Formula: see text]nm. Scanning electron microscopy image shows the presence of a large number of spherical shape nanoparticles having a particle size in the range 2–40[Formula: see text]nm with a few individual nanoparticles larger than 128[Formula: see text]nm. The transmission spectra of InN NPs suspension have the maximum optical transmission edge at 1378[Formula: see text]nm with bandgap energy was 0.85–1.2[Formula: see text]eV. InN has high electrical conductivity that depends on temperature value with small activation energy at room temperature ranging from 0.0318[Formula: see text]meV to 0.1591[Formula: see text]meV.

Effect of Heat Treatment on the Electrical Properties of Thin Yttrium-Doped In2O3 Films

Thin indium oxide films and In–Y–O films containing 0.7 to 3.6 at % Y have been grown by ionbeam sputtering of an indium target and a composite (indium + weighed amounts of yttrium) target in a mixture of argon and oxygen. The thin indium oxide films have a cubic crystal structure (sp. gr. Ia $$\bar 3$$ ). The incorporation of yttrium atoms into indium oxide leads to the formation of an amorphous structure in the as-grown films and an increase in their room-temperature electrical resistance by several orders of magnitude. Lowtemperature electrical resistance data indicate a change in conduction mechanism. High-temperature heat treatment of the thin In–Y–O films leads to the crystallization of their amorphous structure and an increase in their electrical resistance.

Band Gap and Raman Shift of InN Grown on Si (100) by Radio-Frequency Sputtering

We have grown the InN films with high orientation and various typical micrographs on Si (100) substrate by radio-frequency (RF) sputtering, with Indium used as Indium target, and Nitrogen as Nitrogen source. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) show that all the diffraction peaks are identified to be associated with the wurtzite phase of InN, with high orientation of (101), (100) and (002). The Scanning Electron Microscope (SEM) and Energy Diffraction Spectrum (EDS) reveal that the high-quality crystal films of InN with various typical microstructures could be deposited, especially the standard of the hexagon at 60 W and 0.4 Pa. We also calculated the stress of InN films in E 2 (High) by Raman spectra with an excitative wave length λ= 633 nm at room temperature. The values of the stress are different due to various microstructures. The A 1 (LO) peaks are lower due to the high mobility. The calculated energies are 1.07, 1.13 and 1.32 eV. The XRD, SEM, XPS, Raman spectra, Hall and UV absorption characterizations demonstrate that we could grow different microstructures of thin films to meet the various requirements of sensors and other devices.

Fabrication and Properties of InN NPs/Si as a photodetector

Indium nitride InN nanoparticles NPs are synthesized by laser ablation of indium target in ammonium hydroxide solution. The scanning electron microscope SEM, Fourier transforms infrared spectroscopy FTIR, and UV-VIS-NIR spectroscopy were used for investigating the NPs. The FTIR exhibit the presence of In=N bond. The SEM image shows a spherical shape of NPs. The transmission spectra have the maximum edge at 1378nm with band gap was 1.1eV. For optoelectronic properties, InN NPs colloidal was deposited on silicon substrates by drop casting. The characteristics of InN/Si heterojunction have a good rectifying with the spectral Responsivity 0.31 A/W at 750nm and quantum efficiency about 52.7 %.

In-rich AlxIn1−xN grown by RF-sputtering on sapphire: from closely-packed columnar to high-surface quality compact layers

The structural, morphological, electrical and optical properties of In-rich AlxIn1−xN (0 < x < 0.39) layers grown by reactive radio-frequency (RF) sputtering on sapphire are investigated as a function of the deposition parameters. The RF power applied to the aluminum target (0 W–150 W) and substrate temperature (300 °C–550 °C) are varied. X-ray diffraction measurements reveal that all samples have a wurtzite crystallographic structure oriented with the c-axis along the growth direction. The aluminum composition is tuned by changing the power applied to the aluminum target while keeping the power applied to the indium target fixed at 40 W. When increasing the Al content from 0 to 0.39, the room-temperature optical band gap is observed to blue-shift from 1.76 eV to 2.0 eV, strongly influenced by the Burstein–Moss effect. Increasing the substrate temperature, results in an evolution of the morphology from closely-packed columnar to compact. For a substrate temperature of 500 °C and RF power for Al of 150 W, compact Al0.39In0.61N films with a smooth surface (root-mean-square surface roughness below 1 nm) are produced.

A study of crystallographic phases in non-stoichiometric (oxygen deficiency) indium oxide thin films

Indium oxide is a well-known transparent conductive oxide (TCO) in its stoichiometric composition (In2O3). Its electrical and optical properties are strongly influenced by the chemical composition. This work focuses on an experimental investigation of the crystallographic phases in non-stoichiometric (oxygen deficiency) compositions of indium oxide thin films. The thin films were deposited at 300 °C by reactive sputtering of pure indium target at different oxygen gas flow rates on Si substrates. Two different phases are identified only in the non-stoichiometric compositions: metallic indium- and crystalline indium-rich oxide. The metallic indium phase appears as nano-crystals, a few nano-meters in diameter, evenly dispersed and occupies only 1 vol. % of the film. These metallic nano-particles have a negligible effect on the optical transparency and electrical conductivity of the films. The indium-rich oxide (InxOy) phase which occupies about 99 vol. % of the film has the bixbyite crystallographic structure and average grain size of about 50 nm. This phase has a pronounced effect on improving the TCO figure-of-merit (FM) relative to stoichiometric crystalline In2O3 films due to a higher increase of the electrical conductivity than the decrease of the optical transparency.

Characterization of InN nanoparticles prepared by laser as photodetector

Indium nitride (InN) nanoparticles (NPs) are a potentially important material for optoelectronic and high speed electronic devices. Using 1064 nm Nd:YAG laser, InN NPs suspension has been prepared by laser ablation of indium target submerged under ammonium hydroxide. FTIR determined the presence of In=N at 1114.8 cm[Formula: see text] symmetric stretching mode, and In–N bending vibration mode appears at 445.5 cm[Formula: see text]. X-ray diffraction (XRD) observed the peaks (101), (110), and (220) as a reflection formation cubic InN, with an average size of 2 nm. Scanning electron microscope (SEM) image shows that the NPs have a spherical shape with particle size in the range 2–20 nm. The transmission spectra of InN NPs suspension have the maximum optical transmission edge at 1378 nm with the band gap energy of 1.2 eV. The current–voltage characteristics of InN/Si heterojunction have a good rectifying property with a spectral responsivity of about 0.797 A/W at 750 nm wavelength.

Chalcogenide solar cells fabricated by co-sputtering of quaternary CuIn0.75Ga0.25Se2 and In targets: Another promising sputtering route for mass production

In this work, Cu(In1−xGax)Se2 (CIGS) absorber layer is fabricated via radio-frequency sputtering of standard quaternary CuIn0.75Ga0.25Se2 target. In order to achieve the desired Cu-poor absorber film stoichiometry, which is crucial for the device performance, indium is supplied simultaneously with the CIGS deposition by direct current sputtering of indium target for the first time. The influences of sputtering power on composition, structure of the CIGS absorber films and the performances of related solar cells are systematically investigated. The precursor absorber film exhibits uniform and compact surface morphology without peeling and cracking. After selenized in a tube-type rapid thermal processing system under a Se atmosphere, the CIGS absorber layer possesses columnar grains with preferred (112) orientation. Photoelectric measurements of the most efficient device with CdS buffer and ZnO window layer reveals a short-circuit current of 32.02 mA/cm2, an open-circuit voltage of 532 mV, and a fill factor of 60.5 under standard conditions. The efficiency of up to 10.29% on 0.35 cm2 area without antireflection coating has been achieved. Our new sputtering route shows great potential for practical applications of thin film CIGS solar cells with in-line sputtering processes.

INFLUENCE OF ANNEALING TREATMENT ON THE PHYSICAL PROPERTIES OF InAlN FILMS

In this work, pure indium and aluminum targets were co-sputtered in a reactive argon–nitrogen environment at 200°C to deposit InAlN film on the GaAs substrate in the presence of a ZnO buffer layer. The as-grown film was annealed at 750°C for 1 h in a high temperature furnace under nitrogen ambient. XRD pattern of the as-grown film did not display any diffraction peak relating to the InAlN due to its poor structural crystallinity, however, the annealed film exhibited InAlN diffraction peaks corresponding to (002), (101) and (102) planes. A significant increase in the grain size and the surface roughness was observed after the films' annealing. Raman spectroscopy revealed A1 (LO) and E2 (high) phonon modes whereas the PL analysis showed a luminescence peak at 2 eV in the annealed film. The Hall measurements indicated an increase in the carrier concentration and electron mobility after the annealing which was accompanied by a decrease in electrical resistivity of the film. The dark current–voltage (I–V) characteristics of the as-grown and the annealed films were also recorded to investigate the barrier height and the ideality factor.