In light of growing demand and pollution versus a finite amount of resources, electronic waste recycling is a way towards material circularity. New recycling technologies not only face technical difficulties but also need to overcome challenges of feasibility in both economic and environmental aspects. An assessment regarding environmental impacts and economic factors at the early development stages of such technologies is necessary to ensure a successful establishment. A batch lab-scale process using bioleaching to win indium from electronic waste was drafted using recent research in the field. Life Cycle Assessment (LCA) was used to determine the environmental impacts in four different categories at the lowest Technology Readiness Level (TRL). The findings were then compared to two existing chemical leaching processes to put them in perspective. Results show that the electricity consumption is the major contribution to environmental impacts. The assumed bioleaching process has a higher environmental impact than the two chemical processes due to its high duration and resulting high electricity consumption. However, the research has also proven, that an LCA during the conceptual phase has a high uncertainty due to lack of data and knowledge about the process.

Nanoparticles have great potential for biomedical applications such as early detection, accurate diagnosis, and personalized treatment of cancer. Assessment of bio-compatibility and toxicity of nanoparticles body is an emerging topic for these applications. To study kinetics of nanoparticles in body, we synthesized indium, gold and platinum nanoparticles in aqueous suspension using pulsed electrical discharge plasmas in water. The average size of synthesized primary nanoparticles for indium, gold, and platinum are 6.2 nm, 6.7 nm, and 5.4 nm, whereas the average size of secondary nanoparticles for indium, gold, and platinum are 315 nm, 72.3 nm, and 151 nm, respectively. Synthesized indium nanoparticles are transported from subcutaneous to serum and brain. The indium content in serum for the synthesized nanoparticles is much higher than that for the In2O3 nanoparticles of 150 nm in primary size. For gold and platinum nanoparticles, preliminary examination of intratracheal administration revealed that administration of synthesized nanoparticles with 10 mg/kg BW (body weight) may cause bleedings and/or emphysema in lung.

We studied the pulmonary toxicity of indium hydroxide (In(OH)3), which is produced during a recycling process of indium-tin oxide (ITO), in comparison with that of ITO or indium oxide (In2O3), two raw materials of flat panel displays. One hundred and forty-four male Wistar rats were intratracheally given equivalent doses of 10 mg/kg indium as In(OH)3, ITO, or In2O3 particles, twice a week, for a total of 5 times for 2 weeks. Control rats were given distilled water as a vehicle. After 3 weeks, these rats were serially euthanized, and toxicological effects were determined. Body weight gain was significantly suppressed in the In(OH)3-treated rats compared to that in the control group, but not in the ITO- or In2O3-treated rats. Relative lung weights in all the indium-treated groups significantly increased compared to those in the control group throughout the observation period. Furthermore, lung weights in the In(OH)3 group were significantly higher than those in either the ITO or In2O3 group. Blood indium levels in the In(OH)3-treated rats were much higher, 70- to 200-fold, than those in the In2O3- or ITO-treated rats at each time point. Although the lung indium content decreased gradually during the observation periods, the content in the In(OH)3 group was significantly higher than that in either the ITO or In2O3 group. A histopathological analysis revealed foci indicating a slight to severe pulmonary inflammatory response, including exudation to alveolar spaces, were present in all the indium-treated groups. Interstitial fibrotic proliferation was seen only in the In(OH)3-treated rats. The severity of these lesions in the In(OH)3-treated rats was greater than that in either the ITO- or In2O3-treated rats.

The results of our study clearly demonstrated that In(OH)3 particles caused severe pulmonary toxicity when repeated intratracheal instillations were performed in rats. Furthermore, the toxic potency of In(OH)3 in the lung was much higher than that of ITO and In2O3. Accordingly, the toxicity of In(OH)3 particles should be considered in addition to that of ITO and In2O3 particles when indium exposure occurs.

Over the past 12 years, photovoltaics enjoyed an average growth of ∼45% per year that was affected only marginally by the recent global financial crisis. Industrial roadmaps and analysts’ forecasts share visions of solar power becoming a major contributor to national and global electricity grids, with several terawatts of cumulative deployment by 2050 or earlier. For photovoltaics technology to become a major sustainable player in a competitive power-generation market, it must provide abundant, affordable electricity, with environmental impacts dramatically lower than those from conventional power generation. This article summarizes the prospects in each of three basic aspects of sustainability, namely, system costs, environmental impacts, and resource availability, all of which are examined in the context of prospective life-cycle assessment. Indeed, these three aspects are closely related: Increasing the efficiency of material recovery by recycling spent modules will become increasingly important in resolving cost, resource, and environmental constraints on large-scale sustainable growth.

TiN–indium composite films were deposited by simultaneous sputtering of titanium and indium in a mixed Argon/Nitrogen atmosphere and characterized for tribological applications. Film compositions showed a nonlinear behavior as a function of sputter gun power. For films deposited at −50 V bias, and containing less than 29 relative percent indium, the films had a face centered cubic structure, but at higher indium contents (63–82%) the structure was not consistent with either TiN or indium. At −150 V bias, the films had either the TiN structure, In-type structure, or a mixture of the two. Atomic force microscopy images showed the formation of semispherical drops on the surface of the samples deposited at −50 V bias voltage, whereas at −150 V bias voltage the samples exhibited a smooth coating surface with occasional ellipsoidal blisters. Nanoindentation test of the films shows low hardness (5–12 GPa), but tribological testing showed that frictional behavior can be improved by moderate heating before testing, suggesting indium segregation to the surface.

The electromigration (EM) behavior of the Cu/Sn–In/Cu solder model strip was investigated under the conditions of high electrical current density (10 kA/cm2) at various temperatures. The composition of indium (In) was 0, 4, 8, and 16 in wt%. The interconnection of Sn–In solder alloys with a Cu substrate was prepared by reflow soldering at 250 °C. Microstructural analysis confirmed that primary intermetallic compound formed at the interface of the Cu/Sn–In strip was Cu6(In,Sn)5 regardless of In contents. Sn grain size became finer as In content increased. After current stressing, electrical failure was caused by the formation of voids and cracks at the cathode because of the migration of Cu atoms. Sn–16In alloy that has fine grain structure exhibits excellent EM resistance primarily due to the retardation of Cu migration.

It is well-known that cadmium and its corrosion product (cadmium oxide) are carcinogenic and toxic. Consequently, efforts to eliminate cadmium from original equipment and repair processes have been on-going. One potential replacement is indium, which is a soft post-transition metal, whose primary use is in the form of indium tin oxide, e.g., in liquid crystal displays (LCDs). The semi-conductive properties of indium oxide alloys make it possible to use these for cadmium brush plating replacement in applications where contact resistance and impedance are critical parameters. Critical requirements of an alternative to cadmium brush plating in a corrosive industrial atmosphere are (1) be sacrificial to mild steel and (2) provide good electrical conductivity. Cadmium oxide remains semi-conductive, while most other pure metal oxides are electrical insulators, such as aluminum oxide, nickel oxide, and zinc oxide, and therefore, fail in meeting the requirement for bonding and grounding. Similar to cadmium oxide, indium oxide is semi-conductive, but indium exhibits other properties such as cold welding. This paper discusses indium- electroplating approaches to overcome the insulating limitation of pure metal plating and to replace cadmium brush plating. Test results are given for the brush-plated indium-tin alloy as compared to cadmium brush plating and conclusions on such replacement feasibility are provided.

The Czochralski pulling process is the most valuable and cost efficient method for producing large oriented single crystals of the group IV and III-V semiconductors. However, there have been only a small number of reported attempts to use the Czochralski process for growing the wide bandgap compound semiconductors, needed for the room temperature operated gamma-ray detectors. The main difficulty is in the low chemical stability and high vapor pressure of the group II, V and VI elements, leading to off-stoichiometric composition, and various related defects. Among the heavy metal halides, indium iodide and indium bromide present an interesting exception. InI has a high molecular disassociation energy and a low vapor pressure, allowing for Czochralski pulling. We will describe the procedures used and the results obtained by Czochralski growth and characterization of indium iodide and the related ternary compounds that appear to be quite encouraging.

Chalcopyrite solar cells based on CuInSe2 and associated alloys have demonstrated high efficiencies, with current annual shipments in the hundreds of megawatts (MW) range and increasing. Largely due to concern over possible indium (In) scarcity, a related set of materials, the kesterites, which comprise Cu2ZnSnS4 and associated alloys, has received increasing attention. Similarities and differences between kesterites and chalcopyrites are discussed as drawn from theory, depositions, and materials characterization. In particular, we discuss predictions from density functional theory, results from vacuum co-evaporation, and characterization via x-ray diffraction, scanning electron microscopy, electron beam-induced current, quantum efficiency, secondary ion mass spectroscopy, and luminescence.

We present the results of an electrical injection study of spin polarized electrons from ferromagnetic Fe contacts into electronic shells of self-assembled InAs quantum dots (QDs) incorporated in GaAs/AlGaAs spin LED structures. The circular polarization of the emitted light was measured as function of current and magnetic field. The polarization of the EL spectra exhibits strong maxima at energies that do not coincide with the electroluminescence (EL) intensity peaks. The magnetic field dependence of the polarization maxima is consistent with spin injection from the ferromagnetic Fe contacts. The experimental results are compared with calculated emission spectra from multi-exciton complexes (N = 2 and N = 6) as function of electron spin polarization. The energies of the EL features as well as their polarization characteristics are understood in terms of energy shifts due to exchange interactions between spin-down electrons occupying adjacent shells.

Thin films of CuInSe2 (CIS) and CuGaSe2 (CGS) were deposited on (100) Si substrates by RF magnetron sputtering using stoichiometric targets, at various substrate temperatures. Prior to film deposition, the Si substrates were cleaned using the RCA cleaning procedure and treated in a buffered oxide etch (BOE) solution. Deposited films were characterized using Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM) of cross-sectional samples and Hall measurements. Rutherford backscattering analysis indicated that the CIS films had a composition of Cu0.8In1.1Se1.9, whereas CGS films were Cu-poor and Ga-rich with a composition of Cu0.3Ga1.5Se1.5. Clean Cu-chalcopyrite/Si interfaces were obtained using BOE treated Si substrates. Transmission electron micrographs of cross-sectional samples indicated a polycrystalline film structure and that the native oxide on the Si substrate was eliminated. Energy dispersive X-ray spectroscopy (EDS) conducted in the TEM showed that contamination levels in the films were low. The Hall-mobility experiments performed the CIS film indicated that the material was of p-type conductivity with a carrier concentration of 9.6 x 1020/cm3 and a Hall mobility of 390 cm2V-1s-1.

The dynamics of strongly driven phase transitions at surfaces are studied by ultra-fast time-resolved reflection high energy electron diffraction. The surfaces are excited by an intense fs-laser pulse (pump) and probed by an ultra-short electron pulse with variable time delay. The order-disorder phase transition from a c(4×2) to a (2×1) of the bare Si(001) surface shows a transient decrease of the intensity of the c(4×2) spots which recovers on a time scale of a few hundred picoseconds indicating the excitation of the phase transition. On Si(111) a monolayer of Indium induces a (4×1) reconstruction which undergoes a Peierls like phase transition to a (8ד2”) reconstruction below 100 K. Upon laser excitation at a temperature of 40 K the phase transition was strongly driven. The (8ד2”)-diffraction spots instantaneously disappears, while the intensity of the (4×1)-spots increases. This increase of the (4×1) spot intensity excludes an explanation by the Debye-Waller-Effect and is evidence for a true structural phase transition at a surface.

Fe-doped In2O3 nanocubes were synthesized by a solvothermal method. The lattice constant a decreases linearly as Fe doping concentration increases, and Raman scattering measurement proves the incorporation of Fe ions into the In2O3 crystal lattice. Mössbauer spectra show the presence of mixed valence of Fe ions instead of Fe3O4, while the sample is superparamagnetic. The products with an average diameter of 80 nm have a single-crystalline phase and appear as a square shape. Magnetic measurements confirm the superparamagnetic properties of the nanocubes, and electron paramagnetic resonance studies indicate Fe ions occupy different sites in the In2O3 matrix.

Nitride based Distributed Bragg Reflectors (DBRs) have several important applications in current nitride based optoelectronic devices. DBRs can be implemented in resonant cavity light emitting diodes (RCLEDs) to improve light extraction and obtain a more directional emission and in vertical cavity surface emitting lasers (VCSELs) to achieve a lower threshold current. Due the large contrast in refractive index, AlN/GaN DRBs are practical for obtaining high reflectivity and wide bandwidth using relatively few periods. Cracking of the samples is typical for AlN/GaN DRBs due to the tensile strain which results from the 2.4% lattice mismatch and to the difference in thermal expansion coefficients. In addition to cracks, v-shaped defects may also arise in the surface due to surface undulation from stored elastic misfit strain or from threading dislocations that result in scattering and diffraction. Several techniques to reduce the number of cracks and defects have been investigated to obtain smooth surface morphology and high reflectivity, e.g. superlattices to reduce the strain or the growth of AlInGaN/GaN DBRs that offer less lattice mismatch but also lower refractive index contrast. In this work, results of the use of Indium (In) as a surfactant in Metal Organic Vapor Phase Epitaxy (MOVPE) will be discussed. This study addresses AlN/GaN DBR structures designed for peak reflectivity around 465 nm. During the AlN layers’ growth, trimethylindium was introduced to the system and resulted in a reduction of surface cracks. Results of growths at In flow rates are reported and discussed.

We have grown indium nitride (InN) films using In buffer layer on an a-plane sapphire substrate under atmospheric pressure by halide CVD (AP-HCVD). Growth was carried out by two steps: deposition In buffer layer at 900 °C and subsequent growth of InN layer at 650 °C. In order to compare, we also grown InN films on an a-plane sapphire. The InN films are investigated on crystal quality, surface morphology and electrical property using high-resolution X-ray diffraction (HR-XRD), X-ray pole figure, scanning electron microscope (SEM), Hall measurement. The results show that the crystal quality, surface morphology and electrical property of InN films are improved by using In buffer layer.

Indium in Pb1-xSnxTe alloys forms a resonant energy level in the conduction or valence bands, depending on x. In this study we investigate temperature dependence of the In level from 80 to 400K, complementing our previous work at 80 K. Measurements of electrical resistivity, thermopower, Hall and transverse Nernst-Ettinghausen effect are used to assess carrier mobility, Fermi level and scattering coefficient. Measurements are performed on a set of p and n type Pb1-xSnxTe:In with 0 < x < 30 at% and In up to 3 at%. We show that with increasing temperature the Fermi level crosses into the gap. It had been suggested theoretically that hybridization of the In level with one band at the Fermi level could have had a positive effect on the thermoelectric properties of materials, but the present results illustrate the need for temperature-dependent modeling and experimentation.

We compare the electroluminescence (EL) of three polycrystalline ZnO/CdS/Cu(In,Ga)Se2 heterojunction solar cells with similar bandgaps but different open circuit voltages, indicating a difference in the electronic quality of the absorber. Temperature dependent electroluminescence measurements reveal that all cells feature transitions from donor-acceptor pair recombination at lower temperatures to band to band recombination at higher temperatures. However, the less efficient cells show a longer transition range with donor-acceptor pair recombination still apparent at room temperature. The thus broadened room temperature luminescence is one effect which reduces the open circuit voltage of the devices below the Shockley-Queisser-limit. The other effect is the existence of non-radiative recombination currents, which determine the efficiency of the device as light emitting diode. To quantify the open circuit voltage losses, we use reciprocity relations between electroluminescent and photovoltaic action of solar cells, which allow us to predict the light emitting diode efficiency. Measurements support the theory and show that Cu(In,Ga)Se2 solar cells reach external LED efficiencies approaching.

Sn–In alloys are promising low-melting-point Pb-free solders. Cu and Ni are common substrates in the electronic products. This study examines the interfacial reactions in the Sn–20 at.% In(γ–InSn4)/Cu and Sn–20 at.% In/Ni couples at 160 °C. Only the η–Cu6Sn5 phase layer is formed in the Sn–20 at.% In/Cu couple, and the layer grows thicker with longer reaction time. The reaction path is γ–InSn4/η–Cu6Sn5/Cu. A peculiar phenomenon with the bulging of the couple near the Ni substrate is found in the Sn–20 at.% In/Ni couple. A liquid phase is formed by interfacial reaction in the solid/solid Sn–20 at.% In/Ni couple at 160 °C, and the reaction path is γ–InSn4/liquid/δ–Ni3Sn4 + liquid/(δ–Ni3Sn4)/Ni. Usually Ni has a slower reaction rate with solders; however, the consumption rates of Ni substrate are much higher than those of Cu substrate in this study when they are in contact with the Sn–20 at.% In alloy at 160 °C due to the formation of the liquid phase in the Sn–20 at.% In/Ni couple.

In the thin film transistor fabrication process, tin doped indium oxide (ITO) or zinc doped indium oxide (IZO) film can be easily exposed to hydrogen-containing plasma during the deposition of silicon nitride (SiNx) film. By this exposure, ITO or IZO can be easily reduced into its corresponding metallic element such as indium, which degrades the optical transmittance and the conductivity. In this study, SiNx was deposited onto ITO or IZO film, and the oxygen reduction of ITO or IZO during PECVD SiNx deposition was analyzed to clarify this phenomenon. The oxygen reduction during PECVD SiNx deposition is mainly induced by decomposed NH3 gas. However, the progress of ITO reduction is different from that of IZO reduction, due to the different atomic composition of In2O3 in the composite and the different critical temperature of reduction initiation between indium oxide, tin oxide, and zinc oxide.