Indium Atoms Research Articles

Electrical properties and thermal stability in stack structure of HfO2/Al2O3/InSb by atomic layer deposition

Changes in the electrical properties and thermal stability of HfO2 grown on Al2O3-passivated InSb by atomic layer deposition (ALD) were investigated. The deposited HfO2 on InSb at a temperature of 200 °C was in an amorphous phase with low interfacial defect states. During post-deposition annealing (PDA) at 400 °C, In–Sb bonding was dissociated and diffusion through HfO2 occurred. The diffusion of indium atoms from the InSb substrate into the HfO2 increased during PDA at 400 °C. Most of the diffused atoms reacted with oxygen in the overall HfO2 layer, which degraded the capacitance equivalent thickness (CET). However, since a 1-nm-thick Al2O3 passivation layer on the InSb substrate effectively reduced the diffusion of indium atoms, we could significantly improve the thermal stability of the capacitor. In addition, we could dramatically reduce the gate leakage current by the Al2O3 passivation layer. Even if the border traps measured by C–V data were slightly larger than those of the as-grown sample without the passivation layer, the interface trap density was reduced by the Al2O3 passivation layer. As a result, the passivation layer effectively improved the thermal stability of the capacitor and reduced the interface trap density, compared with the sample without the passivation layer.

Effect of Sodium on the Properties of Ag(In, Ga)Se2 Thin Films and Solar Cells

Ag(In, Ga)Se2 (AIGS) thin films were deposited by a modified three-stage method, using a molecular beam epitaxy apparatus. The influence of sodium on the properties of AIGS films was investigated, using Mo-coated soda-lime-glass (SLG) and quartz as substrates. A sodium concentration gradient was observed along the thickness direction of the AIGS film. This resulted from sodium diffusion from the SLG substrate. No sodium was observed in the AIGS film fabricated on the quartz substrate. The grain size and crystallinity of AIGS increased upon sodium doping. Photoluminescence (PL) experiments on the AIGS film showed that exponentially tailed donor states introduced by indium atoms were passivated by sodium. This led to free excitons being observed in the PL spectrum. Potential fluctuation was used to explain the emission spectra of both sodium-containing and sodium-free samples. The donor and acceptor levels included in the quasi-donor–acceptor pair recombination were observed at approximately 35 meV interstitial defect (GaAg) and 100 meV ( V Se), respectively. Solar cell performance was significantly improved by sodium doping, probably because of defect passivation.

Sensitive elemental detection using microwave-assisted laser-induced breakdown imaging

This study reports a sensitive spectroscopic method for quantitative elemental detection by manipulating the temporal and spatial parameters of laser-induced plasma. The method was tested for indium detection in solid samples, in which laser ablation was used to generate a tiny plasma. The lifetime of the laser-induced plasma can be extended to hundreds of microseconds using microwave injection to remobilize the electrons. In this novel method, temporal integrated signal of indium emission was significantly enhanced. Meanwhile, the projected detectable area of the excited indium atoms was also significantly improved using an interference-, instead of diffraction-, based technique, achieved by directly imaging microwave-enhanced plasma through a novel narrow-bandpass filter, exactly centered at the indium emission line. Quantitative laser-induce breakdown spectroscopy was also recorded simultaneously with the new imaging method. The intensities recorded from both methods exhibit very good mutual linear relationship. The detection intensity was improved to 14-folds because of the combined improvements in the plasma lifetime and the area of detection.

G-quadruplex and calf thymus DNA interaction of quaternized tetra and octa pyridyloxy substituted indium (III) phthalocyanines

The interactions of small molecules with G-quadruplex and double stranded DNA are important due to their potential biological and medical usages. In the present paper, the interactions of indium (III) phthalocyanines (quaternized 2,3,9,10,16,17,23,24-octakis-[(3-pyridyloxy) phthalocyaninato] chloroindium(III): OInPc and quaternized 2(3),9(10),16(17),23(24)-tetrakis-[(3-pyridyloxy) phthalocyaninato] chloroindium(III): TInPc) with hybrid G-quadruplex (Tel 21) and parallel G-quadruplexes (nucleolin, KRAS, c-MYC, vegf) were studied. The interactions of these phthalocyanines with ctDNA were also investigated. These interactions were measured by different spectroscopic techniques such as UV–Vis, fluorescence and circular dichroism. The UV–Vis spectroscopic data treated with Benesi-Hildebrand equation and Benesi-Hildebrand constants (KBH) were calculated. These constants were found higher for octa peripheral pyridyloxy substituted phthalocyanine, OInPc. Besides, UV–Vis analysis showed that the interaction of G-quadruplexes with tetra peripheral pyridyloxy substituted phthalocyanine derivative (TInPc) resulted in removal of central indium (III) atom from the cavity of phthalocyanine macrocycle. The UV–Vis melting studies as well as fluorescence replacement techniques were also employed for clarification of mechanism. The binding mode of molecules with ct DNA was also supported with viscosity measurements. From the results, the stabilization and destabilization of G-quadruplex depending on the concentration of the OInPc and TInPc showed that these two indium (III) phthalocyanines have the potential of both the elucidation role of G-quadruplexes in gene expression and the usage in cancer therapy.

Strain modulations of magnetism in Fe-doped InSe monolayer

First-principles calculations are performed to investigate the electronic and magnetic characteristics of Fe-doped two-dimensional (2D) InSe monolayer by applying biaxial compressive and tensile strains. Our studies show that Fe substituting indium atom can be realized easily under Se-rich experimental environments, and can induce the magnetic semiconducting characteristics. Interestingly, the magnetic moments are insensitive to the strain ~ −6% to 6% range. However, loading larger tensile strain can decrease the magnetic moments sharply. Moreover, the system still retains semiconducting characteristics under compressive strain, while a transition occurs from semiconductor to metal beyond the tensile strain 8%. These results provide the theoretical predications that Fe-doped 2D InSe material may be applied in the spintronic devices.

Equiatomic indides REIrIn (RE=La, Pr, Nd, Er–Yb) – Crystal and electronic structure

Abstract The equiatomic rare earth iridium indides REIrIn (RE=La, Pr, Nd, Er–Yb) were synthesized by reaction of the elements in induction or muffle furnaces and were characterized through X-ray powder patterns. The structures of LaIr0.86In1.14, PrIr0.89In1.11, NdIr0.94In1.06, ErIrIn (all ZrNiAl type, P6̅2m), and YbIrIn (TiNiSi type, Pnma) were refined from single crystal X-ray diffractometer data. Refinements of the occupancy parameters revealed small degrees of solid solutions with indium substitution on the iridium sites. Chemical bonding analyses and electronic structure calculations indicate the dominance of metallic bonding in addition to partial ionic interactions between the cations and polyanions, as well as covalent contributions between the indium and iridium atoms.

Impact of dispersion forces on matter-wave scattering near a dielectric disk

The influence of the Casimir-Polder potential upon matter-wave scattering near a dielectric disk is considered. We employ a rescaled Dyson series in order to take into account the disk geometry, and compare this with a previously used approach based on the proximity-force approximation. In the latter approach one uses a simplified potential that is sharply switched on in the region of the disk. This intrinsically neglects edge and saturation effects. We show that under appropriate conditions the previous simpler model works very well for the calculation of the phase accumulated along the full path of the particle due to approximate cancellations of the errors. We present specific results for experimentally relevant scenarios, namely indium atoms or deuterium molecules interacting with a silicon nitride or silicon dioxide disk. Finally we compare our calculations to the analytically solvable problem of an infinitely thin perfectly reflecting disk, finding the expected qualitative agreement.

Interface chemistry study of InSb/Al2O3 stacks upon in situ post deposition annealing by synchrotron radiation photoemission spectroscopy

The thermal stability of InSb/Al2O3 stacks has been systematically studied upon in situ post deposition annealing (PDA) at 300°C and 400°C. Atomic layer deposition (ALD) of Al2O3 (∼3nm) has been grown on the native oxide and the HCl aqueous solution treated InSb (100) at 200°C. The interface chemistry, elemental diffusion as well as elemental desorption are characterized by synchrotron radiation photoemission spectroscopy (SRPES) with the incident photon energy of 750, 600 and 500eV. A Math model has been proposed to calculate the depth profile for In and Sb oxides based on the analysis from different incident energies. Indium atoms have re-oxidized during ALD process, and indium oxide has been observed to diffuse into the Al2O3 film upon PDA at 300°C for the HCl pretreated sample. Indium oxide has desorbed and diffused upon PDA process for the native oxide sample. Sb oxide has been observed to desorb continuously as PDA temperature increases, for all samples. The surface has been torn up upon PDA at 400°C from the morphology characterization.

EuAuGe Type IndidesRAgIn (R= Ca, Sr, La, Eu)

The equiatomic intermetallic phases CaAgIn [a = 482.75(7), b = 750.0(1), c = 835.5(1) pm], SrAgIn [a = 495.86(5), b = 794.71(9), c = 851.89(9) pm], LaAgIn [a = 489.99(5), b = 767.93(9), c = 837.53(9) pm], and EuAgIn [a = 493.02(7), b = 781.6(1), c = 844.2(1) pm] were synthesized from the elements in sealed niobum containers. They crystallize with the EuAuGe type structure, space group Imm2. The four structures were refined from single-crystal X-ray data. The silver and indium atoms build up orthorhombically distorted, puckered Ag3In3 hexagons, which are stacked in AA′ sequence, leading to direct Ag–Ag and In–In interlayer bonding (e.g. 303 and 304 pm in CaAgIn). Temperature dependent magnetic susceptibility measurements show a magnetic moment of 7.40(1) μB per europium atom. EuAgIn orders antiferromagnetically at 5.7(5) K. The divalent nature of europium is also evident from 151Eu Mossbauer spectra: δ = –10.50(1) mm·s–1 at 78 K.

Indium passivation impact on HfO2/GaAs interface: A first-principles study

The interface quality between III–V semiconductor and high-k material is critical for improving the performance of the metal-oxide-semiconductor field effect transistors. Utilizing first-principles calculations, we explore the electronic properties of the GaAs/HfO2 interface when indium interfacial atom defects are introduced. The stability of the interfaces will increase with the increasing of the number of indium interfacial atoms. Meanwhile, the band offsets also depend on the number of indium atom substitutions and interstitials. Furthermore, the substitutions suppress the interfacial gap states near the VBM and have the partially passivation, but the effect of interstitial passivation on the interfacial states are limited.

Effects of substrate pre-nitridation and post-nitridation processes on InN quantum dots with crystallinity by droplet epitaxy

For the growth of InN quantum dots by plasma-assisted molecular beam epitaxy (PA-MBE) via droplet epitaxy technique, the effects of nitridations processes (pre-nitridation on Si (111) substrate and post-nitridation to form InN quantum dots) have been discussed in this report. Pre-nitridation and post-nitridation processes cause lots of impact to the growth mechanism of InN quantum dots. Reflected-high energy electron diffraction (RHEED) analysis can show us the in situ surface condition and assist us to observe the formation of InN quantum dots during the epitaxy. The surface conditions of Si can be modified by the substrate pre-nitridation process, the nitrogen-terminal surface could influence the sticking coefficient and surface diffusion of indium atoms. InN quantum dots with pre-nitridation process grown at temperature 450°C have relatively high dots density, broad size distribution, and shape in some preferred orientation. Meanwhile, the post-nitridation process of droplet epitaxy can reduce the dots density due to desorption, surface diffusion and aggregation phenomena. Finally, high-resolution transmission electron microscopy (HRTEM) provides the crystallinity of InN quantum dots, which is consistent with the result using RHEED. The InN quantum dots are crystallized as wurtzite structure with the lattice constant of 0.572nm. The performance of quantum dots has been investigated by photoluminescence spectra with a peak at 1530nm and a broad-peak around 1130nm.

Ternary aurides La4In3Au10 and Yb4In3Au10 and platinide U4In3Pt10 with ordered Zr7Ni10 type structure

The ternary aurides La4In3Au10 and Yb4In3Au10 and the platinide U4In3Pt10 with ordered Zr7Ni10 type structure were synthesized from the elements by induction-melting in sealed tantalum tubes or via arc-melting. The polycrystalline samples were characterized by powder X-ray diffraction and the structures were refined from single crystal X-ray diffractometer data: Cmce, a = 1426.7(3), b = 1020.3(2), c = 1025.2(2) pm, wR2 = 0.0441, 1510 F2 values, 46 variables for La4In3Au10, a = 1361.5(3), b = 998.3(2), c = 1007.8(2), wR2 = 0.0804, 1404 F2 values, 46 variables for Yb4In3Au10 and a = 1344.4(3), b = 973.9(2), c = 978.9(2), wR2 = 0.0922, 741 F2 values, 48 variables for U4.15In3.03Pt9.82 (with small degrees of In/U, respectively Pt/In mixing on Wyckoff sites 4a and 8f). The La4In3Au10, Yb4In3Au10 and U4In3Pt10 structures contain pronounced two-dimensional gold, respectively platinum substructures which are filled and condensed by two crystallographically independent indium and rare earth atoms. The crystal chemical features clearly classify these intermetallics as aurides and platinides. The physical properties of U4In3Pt10 were characterized by means of magnetic and electrical transport measurements. The compound exhibits metallic conductivity and shows no magnetic ordering down to 1.72K. Its magnetic behavior is governed by hybridization between 5f and ligand electrons that results in significant delocalization of the 5f states.

Preparation of Single-Crystalline AgIn5S8 Octahedrons with Exposed {111} Facets and Its Visible-Light-Responsive Photocatalytic H2 Production Activity.

Although AgIn5S8 as one kind of ternary chalcogenides has been extensively investigated due to its band-edge positions meeting the thermodynamic requirement for water photosplitting, very little attention has been focused on the crystallinity and facet effects of AgIn5S8 on its photocatalytic activity. Herein, a facile hydrothermal route was developed to fabricate regular single-crystalline AgIn5S8 octahedrons with only {111} facets exposed. Also, the effects of the hydrothermal reaction conditions on the composition, crystal phase, crystallinity, and morphology of the obtained AgxInyS(x+3y/2) products (hereafter denoted as AIS-x, where x represents the pH value of the reaction solution) were investigated, and it was found that the accurately released S2- ions from the thermal decomposition of thioacetamide (TAA) is the central factor for the nucleation and growth of the AgIn5S8 octahedrons. The experimental results indicate that the resultant regular AgIn5S8 octahedrons (AIS-10.6) exhibit the best photocatalytic activity for H2 production among those AgxInyS(x+3y/2) products, and the higher crystallinity and fewer defects of the AgIn5S8 octahedrons compared to the other AgxInyS(x+3y/2) products can retard the photogenerated charge recombination, while those indium atoms with higher density in the exposed {111} facets might be beneficial for the photocatalytic H2 production reaction by acting as active sites to promote the charge separation and transfer processes. The results presented here provide new insights into the significance of crystallinity and exposed facets in the visible-light-responsive activity of AgIn5S8, thus paving new ways into the design and synthesis of high-performance, cost-effective AgIn5S8 photocatalysts for H2 production.

Electronic properties of the intermetallic compound Ti2In5 using the density functional theory

The identification of structurally stable phases in the In-Ti system is an open topic and currently there are four confirmed intermetallic phases: Ti3In, Ti3In2, Ti2In5 y Ti5In8. The most studied of this compounds is Ti3In, however, the properties of the others are not well known. For this reason, this work is a study of the electronic properties of the compound Ti2In5 using the density functional theory and the FP-LAPW method. The band structure shows the metallic character of the material, although for some directions in the k-space the electronic bands do not intercept the Fermi level. The density of states shows that in the vicinity of the Fermi level the greatest contribution comes from the d orbital of titanium, showing the importance of Ti in the metallic behavior of the material. The density contour plots shows a great contribution of indium atoms at the basal plane, while above this, but in lower quantity titanium atoms are also distributed. The Fermi surface of Ti2In5 is reported. The cohesive energy and the formation enthalpy were determined, showing an energetic condition that is more favorable than in the pure constituents alone.

Experimental investigation and ab initio calculation of the properties of Sc-, in-doped bismuth titanates with the pyrochlore type structure

Using ab initio calculations, the data have been obtained on the structural, electronic, and optical properties of bismuth titanates with the pyrochlore type structure and compounds with the substitution of scandium or indium atoms for bismuth and titanium atoms. The results of the theoretical calculations agree with the experimentally obtained structural and optical characteristics of the synthesized compounds doped with scandium or indium. It has been shown that the substitution of scandium or indium atoms for bismuth atoms in the pyrochlore structure is energetically favorable. The energies corresponding to the direct and indirect electronic transitions in scandium- and indium-doped bismuth titanates have been determined based on the optical spectroscopy data obtained for the studied samples. These energies are in agreement with the theoretically calculated values.

Mixed-ligand fluorooxalate complex compounds of indium(III) M2[InF3(C2O4)H2O] (M = K, Rb): Synthesis and crystal structure

Isostructural fluorooxalate complex compounds of indium(III) M2[InF3(C2O4)H2O] (M = K, Rb), being the first representatives of a new class of mixed-ligand fluoro-containing complex compounds of indium(III) are synthesized and structurally studied for the first time. The crystal structures of M2[InF3(C2O4)H2O] (M = K, Rb) are formed of K+ cations (Rb+ respectively) and complex [InF3(C2O4)H2O]2– anions. The indium atom in the complex anion is surrounded by four F atoms, two of which are bridging, the oxygen atom of the coordinated H2O molecule, and two oxygen atoms of the bis-bidentate (tetradentate) oxalate group. The coordination polyhedron of the indium atom (CN 7) is a pentagonal bipyramid. Via alternating double bridging F atoms and tetradentate bridging C2O4 group, the In(III) atom polyhedra are arranged in polymers chains. Via hydrogen O–H⋯F bonds the chains are organized in layers. Between the layers, the K+ or Rb+ cations are located, which strengthen the crystal structure.

Layer-separable and gap-tunable topological insulators

The way in which states of a topological insulator (TI) transform from monolayer to bulk is an important issue for applications in spintronics. However, unlike graphite, most layered materials are difficult to exfoliate. Using first-principles calculations, we predict that thallium selenide (TlSe) will be a layered TI with rather weak interlayer coupling and thus it should be exfoliated easily. The evolution of the topological states can also be driven by doping with indium (In) atoms or applying lateral strains. A comparison of TlSe and β-InSe shows that the influences of structural and chemical components on the electronic structures determine the topological phase. Effects of van der Waals interactions in this TlSe material are also addressed.

Crystal structure of fluorosulfate complex compounds of indium(III) M2[InF3(SO4)H2O] (M = K, NH4)

The crystal structures of isostructural mixed-ligand fluorosulfate complex compounds of indium(III) M2[InF3(SO4)H2O] (M = K, NH4), formed of K+ cations, NH4 + respectively, and complex [InF3(SO4)H2O]2– anions are determined. In the complex anion, the indium atom surrounded by three F atoms, the oxygen atom of the coordinated H2O molecule, and two oxygen atoms of the bridging sulfate group forms a slightly distorted octahedron (CN 6). Via alternating bridging SO4 groups, the polyhedra of In(III) atoms are arranged in polymer chains. The O–H•••F hydrogen bonds organize the chains in a three-dimensional network. The K+ and NH4 + cations are located in the structure framework and additionally strengthen it.

Spectroscopic Ellipsometry Study of the Dielectric Function of Cu(In<sub>1–x</sub>Ga<sub>x</sub>)<sub>3</sub>Se<sub>5</sub> Bulk Compounds: Identification of Optical Transitions

Using Spectroscopic Ellipsometry (SE), the optical properties of Cu(In1−xGax)3Se5 bulk compounds, grown by the Bridgman method, were analyzed by varying x composition (0 ≤ x ≤ 1). Energy levels above the gap in the band scheme were determined by measuring the complex dielectric function at room-temperature for energies between 1.5 and 5.5 eV using a variable angle of incidence ellipsometer. The transitions values E1, E2 and E3 were observed above the gap for different samples of Cu(In1−xGax)3Se5 alloy. When a gallium atom replaces an indium atom, one assumes globally that the levels related to selenium and copper are unchanged. Conversely, the levels corresponding to the conduction band are shifted towards higher energies. Thus, the gap increases as the composition of gallium increases. Spectroscopic Ellipsometry (SE) gave evidence for the interpretation of the choice of gap values which were compatible with that obtained from solar spectrum. Several other characterization methods like Energy Dispersive Spectrometry (EDS), hot point probe method, X-ray diffraction, Photoluminescence (PL), Optical response (Photoconductivity) were presented in this paper. The Cu(In1−xGax)3Se5 have an Ordered Vacancy Chalcopyrite-type structure with lattice constants varying as a function of the x composition. The band gap energy of Cu(In1−xGax)3Se5 compounds is found to vary from 1.23 eV to 1.85 eV as a function of x.

Electronic and optical properties of two-dimensional InSe from a DFT-parametrized tight-binding model

We present a tight-binding (TB) model and $\mathbf{k\cdot p}$ theory for electrons in monolayer and few-layer InSe. The model is constructed from a basis of all $s$ and $p$ valence orbitals on both indium and selenium atoms, with tight-binding parameters obtained from fitting to independently computed density functional theory (DFT) band structures for mono- and bilayer InSe. For the valence and conduction band edges of few-layer InSe, which appear to be in the vicinity of the $\Gamma$ point, we calculate the absorption coefficient for the principal optical transitions as a function of the number of layers, $N$. We find a strong dependence on $N$ of the principal optical transition energies, selection rules, and optical oscillation strengths, in agreement with recent observations \cite{Bandurin2016}. Also, we find that the conduction band electrons are relatively light ($m \propto 0.14-0.18 m_e$), in contrast to an almost flat, and slightly inverted, dispersion of valence band holes near the $\Gamma$-point, which is found for up to $N \propto 6$.