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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Superconducting thin films of (100) and (111) oriented indium doped topological crystalline insulator SnTe

Recent discovery of the topological crystalline insulator SnTe has triggered a search for topological superconductors, which have potential application to topological quantum computing. The present work reports on the superconducting properties of indium doped SnTe thin films. The (100) and (111) oriented thin films were epitaxially grown by pulsed-laser deposition on (100) and (111) BaF2 crystalline substrates respectively. The onset superconducting transition temperatures are about 3.8 K for (100) and 3.6 K for (111) orientations, slightly lower than that of the bulk. Magneto-resistive measurements indicate that these thin films may have upper critical fields higher than that of the bulk. With large surface-to-bulk ratio, superconducting indium doped SnTe thin films provide a rich platform for the study of topological superconductivity and potential device applications based on topological superconductors.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Amphoteric Indium Enables Carrier Engineering to Enhance the Power Factor and Thermoelectric Performance in n -Type Ag n Pb 100 In n Te 100+2 n (LIST)

The Ag and In co-doped PbTe, Ag n Pb 100 In n Te 100+2n (LIST), exhibits n-type behavior and features unique inherent electronic levels that induce self-tuning carrier density. Results show that In is amphoteric in the LIST, forming both In 3+ and In 1+ centers. Through unique interplay of valence fluctuations in the In centers and conduction band filling, the electron carrier density can be increased from ≈3.1 × 10 18 cm -3 at 323 K to ≈2.4 × 10 19 cm -3 at 820 K, leading to large power factors peaking at ≈16.0 μWcm -1 K -2 at 873 K. The lone pair of electrons from In + can be thermally continuously promoted into the conduction band forming In 3+ , consistent with the amphoteric character of In. Moreover, with rising temperature, the Fermi level shifts into the conduction band, which enlarges the optical band gap based on the Moss–Burstein effect, and reduces bipolar diffusion and thermal conductivity. Adding extra Ag in LIST improves the electrical transport properties and meanwhile lowers the lattice thermal conductivity to ≈0.40 Wm -1 K -1 . Here, the addition of Ag creates spindle-shaped Ag 2 Te nanoprecipitates and atomic-scale interstitials that scatter a broader set of phonons. As a result, a maximum ZT value ≈1.5 at 873 K is achieved in Ag 6 Pb 100 InTe 102 (LIST).

36 MATERIALS SCIENCE↗
DOE OSTI2015

Absolute Ethanol Embolization of Arteriovenous Malformations in the Periorbital Region

ObjectiveArteriovenous malformations (AVMs) involving the periorbital region are technically challenging clinical entities to manage. The purpose of the present study was to present our initial experience of ethanol embolization in a series of 16 patients with auricular AVMs and assess the outcomes of this treatment.MethodsTranscatheter arterial embolization and/or direct percutaneous puncture embolization were performed in the 16 patients. Pure or diluted ethanol was manually injected. The follow-up evaluations included physical examination and angiography at 1- to 6-month intervals.ResultsDuring the 28 ethanol embolization sessions, the amount of ethanol used ranged from 2 to 65 mL. The obliteration of ulceration, hemorrhage, pain, infection, pulsation, and bruit in most of the patients was obtained. The reduction of redness, swelling, and warmth was achieved in all the 16 patients, with down-staging of the Schobinger status for each patient. AVMs were devascularized 100 % in 3 patients, 76–99 % in 7 patients, and 50–75 % in 6 patients, according to the angiographic findings. The most common complications were necrosis and reversible blister. No permanent visual abnormality was found in any of the cases.ConclusionEthanol embolization is efficacious and safe in the treatment of AVMs in the periorbital region and has the potential to be accepted as the primary mode of therapy in the management of these lesions.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2015

Compact field programmable gate array-based pulse-sequencer and radio-frequency generator for experiments with trapped atoms

We present a compact field-programmable gate array (FPGA) based pulse sequencer and radio-frequency (RF) generator suitable for experiments with cold trapped ions and atoms. The unit is capable of outputting a pulse sequence with at least 32 transistor-transistor logic (TTL) channels with a timing resolution of 40 ns and contains a built-in 100 MHz frequency counter for counting electrical pulses from a photo-multiplier tube. There are 16 independent direct-digital-synthesizers RF sources with fast (rise-time of ∼60 ns) amplitude switching and sub-mHz frequency tuning from 0 to 800 MHz.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2016

Combined Microwave Ablation and Cementoplasty in Patients with Painful Bone Metastases at High Risk of Fracture

PurposeTo retrospectively evaluate the effectiveness of computed tomography-guided percutaneous microwave ablation (MWA) and cementoplasty in patients with painful bone metastases at high risk of fracture.Materials and MethodsThirty-five patients with 37 metastatic bone lesions underwent computed tomography-guided MWA combined with cementoplasty (polymethylmethacrylate injection). Vertebrae, femur, and acetabulum were the intervention sites and the primary end point was pain relief. Pain severity was estimated by visual analog scale (VAS) before treatment; 1 week post-treatment; and 1, 6, and 12 months post-treatment. Functional outcome was assessed by improved patient walking ability. Radiological evaluation was performed at baseline and 3 and 12 months post-procedure.ResultsIn all patients, pain reduction occurred from the first week after treatment. The mean reduction in the VAS score was 84, 90, 90 % at week 1, month 1, and month 6, respectively. Improved walking ability occurred in 100 and 98 % of cases at the 1- and 6-month functional outcome evaluations, respectively. At the 1-year evaluation, 25 patients were alive, and 10 patients (28 %) had died because of widespread disease. The mean reduction in the VAS score and improvement in surviving patients’ walking ability were 90 and 100 %, respectively. No patients showed evidence of local tumor recurrence or progression and pathological fracture in the treated sites.ConclusionOur results suggest that MWA combined with osteoplasty is safe and effective when treating painful bone metastases at high risk of fracture. The number of surviving patients at the 1-year evaluation confirms the need for an effective and long-lasting treatment.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Percutaneous Vertebroplasty for Pain Management in Patients with Multiple Myeloma: Is Radiofrequency Ablation Necessary?

Purpose: This study was designed to investigate the added role of radiofrequency ablation (RFA) to vertebroplasty on the pain management of patients with multiple myeloma (MM). Methods: Thirty-six patients (51–82 years) with vertebral localization of MM were randomly divided into two groups: 18 patients (group A) who underwent RFA and then vertebroplasty, and 18 patients (group B) who underwent only vertebroplasty. Primary endpoints were technical success and pain relief score rate measured by the visual analogue pain scores (VAS) and Roland–Morris Questionnaire (RMQ); secondary endpoint was the amount of administered analgesia. Survival and complications were compared. Results: Technical success was 100 % in both groups. The VAS score (at 24 h and 6 weeks postprocedure) decreased in equal manner for both groups from a mean of 9.1–3.4 and 2.0 for group A and from a mean of 9.3–3.0 and 2.3 for group B; RMQ mean score was 19.8 for group A and 19.9 for group B and decreased to a mean of 9.6 and 8.2 for group A and 9.5 and 8.7 for group B. The amount of medication was equally decreased in the two groups. No statistically significant difference was noted. No major complication occurred and two patients died from other causes. Conclusions: The use of percutaneous vertebroplasty alone appears to be effective for the pain management of the patients with vertebral involvement of multiple myeloma. The use of RFA that includes cost and time does not offer any clear added benefit on the midterm pain management of such patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

T24 HRAS transformed NIH/3T3 mouse cells (GhrasT-NIH/3T3) in serial tumorigenic in vitro/in vivo passages give rise to increasingly aggressive tumorigenic cell lines T1-A and T2-A and metastatic cell lines T3-HA and T4-PA

Cancer cells often arise progressively from “normal” to “pre-cancer” to “transformed” to “local metastasis” to “metastatic disease” to “aggressive metastatic disease”. Recent whole genome sequencing (WGS) and spectral karyotyping (SKY) of cancer cells and tumorigenic models have shown this progression involves three major types of genome rearrangements: ordered small step-wise changes, more dramatic “punctuated evolution” (chromoplexy), and large catastrophic steps (chromothripsis) which all occur in random combinations to generate near infinite numbers of stochastically rearranged metastatic cancer cell genomes. This paper describes a series of mouse cell lines developed sequentially to mimic this type of progression. This starts with the new GhrasT-NIH/Swiss cell line that was produced from the NIH/3T3 cell line that had been transformed by transfection with HRAS oncogene DNA from the T24 human bladder carcinoma. These GhrasT-NIH/Swiss cells were injected s.c. into NIH/Swiss mice to produce primary tumors from which one was used to establish the T1-A cell line. T1-A cells injected i.v. into the tail vein of a NIH/Swiss mouse produced a local metastatic tumor near the base of the tail from which the T2-A cell line was established. T2-A cells injected i.v. into the tail vein of a nude NIH/Swiss mouse produced metastases in the liver and one lung from which the T3-HA (H=hepatic) and T3-PA (P=pulmonary) cell lines were developed, respectively. T3-HA cells injected i.v. into a nude mouse produced a metastasis in the lung from which the T4-PA cell line was established. PCR analysis indicated the human T24 HRAS oncogene was carried along with each in vitro/in vivo transfer step and found in the T2-A and T4-PA cell lines. Light photomicrographs indicate that all transformed cells are morphologically similar. GhrasT-NIH/Swiss cells injected s.c. produced tumors in 4% of NIH/Swiss mice in 6–10 weeks; T1-A cells injected s.c. produced tumors in 100% of NIH/Swiss mice in 7–10 days. T1-A, T-2A, T3-HA and T4-PA cells when injected i.v. into the tail produced local metastasis in non-nude or nude NIH/Swiss mice. T4-PA cells were more widely metastatic than T3-HA cells when injected i.v. into nude mice. Evaluation of the injected mice indicated a general increase in metastatic potential of each cell line in the progression as compared to the GhrasT-NIH/3T3 transformed cells. A new photomicrographic technique to follow growth rates within six preselected 2×2 mm{sup 2} grids per plate is described. Average doubling times of the transformed cells GhrasT-NIH/3T3 (17 h), T1A (17.5 h), T2A (15.5 h), T3-HA (17.5 h) and T4-PA (18.5 h) (average 17.2 h) were significantly faster (P=0.006) than NIH Swiss primary embryonic cells and NIH/3T3 cells (22 h each). This cell series is currently used in this lab for studies of cancer cell inhibitors, mitochondrial biogenesis and gene expression and is available for further study by other investigators for intra- and inter-laboratory comparisons of WGS, transcriptome sequencing, SKY and other analyses. The genome rearrangements in these cells together with their phenotypic properties may help provide more insights into how one tumorigenic progression occurred to produce the various cell lines that led to the highly metastatic T4-PA cell line. - Highlights: • A tumor progression model derived from a new T24 HRAS transformed NIH/3T3 cell line. • T1-A, T2-A, T3-HA, T4PA lines derived from GhrasT-NIH/3T3, T1-A, T2-A, T3-HA tumors. • PCR detected the human HRAS oncogene in T2-A and T4-PA metastatic tumors. • These five new cell lines showed a progressive increase in tumorigenic potential. • New method obtained doubling times using daily photomicrographs of gridded plates.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Improved Value for the Gamow-Teller Strength of the Sn100 Beta Decay

A record number of Sn100 nuclei was detected and new isotopic species toward the proton dripline were discovered at the RIKEN Nishina Center. Decay spectroscopy was performed with the high-efficiency detector arrays WAS3ABi and EURICA. Both the half-life and the β-decay end point energy of Sn100 were measured more precisely than the literature values. The value and the uncertainty of the resulting strength for the pure 0+→1+ Gamow-Teller decay was improved to BGT=4.4-0.7+0.9. A discrimination between different model calculations was possible for the first time, and the level scheme of In100 is investigated further. © 2019 American Physical Society.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Diffusion and interface evolution during the atomic layer deposition of TiO{sub 2} on GaAs(100) and InAs(100) surfaces

Atomic layer deposition is used to form TiO{sub 2} films from tetrakis dimethyl amino titanium and H{sub 2}O on native oxide GaAs(100) and InAs(100) surfaces. The evolution of the film/substrate interface is examined as a function of the deposition temperature (100–325 °C) using ex situ x-ray photoelectron spectroscopy. An increase in the deposition temperature up to 250 °C leads to enhancement of the native oxide removal. For depositions at 300 °C and above, interface reoxidation is observed during the initial deposition cycles but when the films are thicker than 3 nm, the surface oxides are removed steadily. Based on these observations, two distinct film growth regimes are identified; up to 250 °C, layer-by-layer dominates while at higher temperatures island growth takes over. Angle resolved x-ray photoelectron spectroscopy measurements performed on 3 nm TiO{sub 2} film deposited at 325 °C on both surfaces demonstrates a very important difference between the two substrates: for GaAs the native oxides remaining in the stack are localized at the interface, while for InAs(100), the indium oxides are mixed in the TiO{sub 2} film.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Catalytic Activity of Li{sub 1+x}Hf{sub 2–x}In{sub x}(PO{sub 4}){sub 3}-Based NASICON-Type Materials for Ethanol Conversion Reactions

Li{sub 1+} {sub x}Hf{sub 2–x}In{sub x}(PO{sub 4}){sub 3} (x = 0, 0.05, 0.1) materials have been prepared by solid-state reactions and characterized by X-ray diffraction, low-temperature nitrogen adsorption measurements, and scanning electron microscopy. The materials consist of NASICON-type lithium hafnium double phosphates with a hexagonal structure. Milling in a planetary mill has been found to increase the specific surface area of the Li{sub 1+} {sub x}Hf{sub 2–x}In{sub x}(PO{sub 4}){sub 3} materials by almost one order of magnitude (from 1.5 to 13 m{sup 2}/g in the case of LiHf{sub 2}(PO{sub 4}){sub 3}). The materials with a larger surface area exhibit catalytic activity for ethanol dehydration reactions and are less active for ethanol dehydrogenation. Ethanol conversion predominantly yields diethyl ether at low temperatures and ethylene at higher temperatures. The diethyl ether selectivity of the catalytic processes reaches 85% at 350°C, with 60% conversion, and the ethylene selectivity reaches 96% at 510°C, with 100% conversion. Indium doping raises the high-temperature acetaldehyde selectivity from 4 to 8% and leads to the formation of C{sub 4} hydrocarbons as reaction products. C{sub 4} selectivity reaches 15 and 17% in the case of the Li{sub 1.05}Hf{sub 1.95}In{sub 0.05}(PO{sub 4}){sub 3} and Li{sub 1.1}Hf{sub 1.9}In{sub 0.1}(PO{sub 4}){sub 3} materials, respectively (420°C, 97 and 92% conversion, respectively).

36 MATERIALS SCIENCE↗
DOE OSTI2015

Synthesis, characterization and catalytic activity of indium substituted nanocrystalline Mobil Five (MFI) zeolite

Highlights: • In situ modification of the MFI zeolite by incorporation of indium. • The samples were characterized by XRD, FTIR, TGA, UV–vis (DRS), SAA, EDX and SEM. • The incorporation of indium was confirmed by XRD, FT-IR, UV–vis (DRS), EDX and TGA. • Hydroxylation of phenol reaction was studied on the synthesized catalysts. - Abstract: A series of indium doped Mobil Five (MFI) zeolite were synthesized hydrothermally with silicon to aluminium and indium molar ratio of 100 and with aluminium to indium molar ratios of 1:1, 2:1 and 3:1. The MFI zeolite phase was identified by XRD and FT-IR analysis. In XRD analysis the prominent peaks were observed at 2θ values of around 6.5° and 23° with a few additional shoulder peaks in case of all the indium incorporated samples suggesting formation of pure phase of the MFI zeolite. All the samples under the present investigation were found to exhibit high crystallinity (∼92%). The crystallite sizes of the samples were found to vary from about 49 to 55 nm. IR results confirmed the formation of MFI zeolite in all cases showing distinct absorbance bands near 1080, 790, 540, 450 and 990 cm{sup −1}. TG analysis of In-MFI zeolites showed mass losses in three different steps which are attributed to the loss due to adsorbed water molecules and the two types TPA{sup +} cations. Further, the UV–vis (DRS) studies reflected the position of the indium metal in the zeolite framework. Surface area analysis of the synthesized samples was carried out to characterize the synthesized samples The analysis showed that the specific surface area ranged from ∼357 to ∼361 m{sup 2} g{sup −1} and the pore volume of the synthesized samples ranged from 0.177 to 0.182 cm{sup 3} g{sup −1}. The scanning electron microscopy studies showed the structure of the samples to be rectangular and twinned rectangular shaped. The EDX analysis was carried out for confirmation of Si, Al and In in zeolite frame work. The catalytic activities of the synthesized samples were investigated with respect to hydroxylation of phenol, in which catechol and hydroquinone were found to be the major products. It is observed that under all reaction conditions catechol selectivity was higher than the hydroquinone selectivity. In-MFI zeolites were successfully synthesized and were used as an effective catalyst for the hydroxylation of phenol to synthesize catechol and hydroquinone as the major product.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Electromagnetic properties of indium isotopes illuminate the doubly magic character of 100 Sn

Understanding the nuclear properties in the vicinity of 100 Sn, which has been suggested to be the heaviest doubly magic nucleus with proton number Z equal to neutron number N, has been a long-standing challenge for experimental and theoretical nuclear physics. In particular, contradictory experimental evidence exists regarding the role of nuclear collectivity in this region of the nuclear chart. Here, we provide further evidence for the doubly magic character of 100 Sn by measuring the ground-state electromagnetic moments and nuclear charge radii of indium (Z = 49) isotopes as N approaches 50 from above using precision laser spectroscopy. Our results span almost the complete range between the two major closed neutron shells at N = 50 and N = 82 and reveal parabolic trends as a function of the neutron number, with a clear reduction towards these two closed neutron shells. Furthermore, a detailed comparison between our experimental results and numerical results from two complementary nuclear many-body frameworks (density functional theory and ab initio methods) exposes deficiencies in nuclear models and establishes a benchmark for future theoretical developments.

100Sn↗
DOE OSTI2015

Oxidation of GaSb(100) and its control studied by scanning tunneling microscopy and spectroscopy

Atomic-scale knowledge and control of oxidation of GaSb(100), which is a potential interface for energy-efficient transistors, are still incomplete, largely due to an amorphous structure of GaSb(100) oxides. We elucidate these issues with scanning-tunneling microscopy and spectroscopy. The unveiled oxidation-induced building blocks cause defect states above Fermi level around the conduction-band edge. By interconnecting the results to previous photoemission findings, we suggest that the oxidation starts with substituting second-layer Sb sites by oxygen. Adding small amount of indium on GaSb(100), resulting in a (4 × 2)-In reconstruction, before oxidation produces a previously unreported, crystalline oxidized layer of (1 × 3)-O free of gap states.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm–50 nm crystalline indium tin oxide or a 100 nm–150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure–function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Developing CdTe homojunctions applying high throughput deposition

In this project, we attempted to make CdTe homojunctions using single crystal p-type doped substrates and closed-space sublimation epitaxy (CSSE) n-type doped films. The project included modeling which determined the ideal thickness for the n-type layer as being <200 nm. Boules of high concentration indium-doped CdTe and CdSe 0.4 Te 0.6 (CST) were grown using modified vertical Bridgman (MVB) methods. Similarly, iodine-doped CdTe crystals were grown for the first time. Washington State University (WSU) stock phosphorus-doped CdTe was used as the p-type substrate layer. The crystals were characterized by Hall effect and time-resolved photoluminescence (TRPL, for electrical properties), photoluminescence microscopy (for uniformity), X-ray diffraction (for crystal structure), and glow discharge mass spectrometry (GDMS, for dopant and impurity concentration). CdTe:I crystals were also characterized by visible and infrared transmission measurements, and various Cd or Te heat treatments were performed to assess changes in optical and electrical properties. The grown n-type materials – CdTe:In, CdSe0.4Te0.6:In, and CdTe:I – were provided to the National Renewable Energy Laboratory (NREL) for growth of CSSE thick films for characterization by two photon TRPL (for carrier lifetime), electron back-scatter diffraction (EBSD, to assess epitaxy), and Hall effect. Several measurements of secondary ion mass spectroscopy (SIMS) were performed. Nearly 100% of the indium from the crystal was incorporated into the measured thick films, while only ~2-22% of the iodine from the crystal was incorporated. The net result of the diffusion issue is that homojunction devices created using CSSE have a buried homojunction, as indicated by the near infrared peak in the external quantum efficiency (EQE). Various parameterization of front and back contacts suggested that the poor device performance was primarily a result of this buried junction and not due to other effects. There may also be an issue with the CSSE film lifetime in addition to the dopant profile.

14 SOLAR ENERGY↗
DOE OSTI2015

Epitaxial growth of In{sub x}Ga{sub 1-x}N alloy films on sapphire and silicon by reactive co-sputtering of GaAs and indium

In{sub x}Ga{sub 1-x}N alloy films (0.2<x<0.5) were epitaxially grown on c-cut sapphire and Si (100) substrates by reactive co-sputtering of GaAs and indium with 100% nitrogen at a substrate temperature of 600 °C. X-ray diffraction studies show the formation of completely c-axis oriented, single phase alloy films over the studied range of composition. The crystallite size along the growth direction and surface morphology of alloy films, particularly those with higher indium fraction exhibit substantial improvement on Si (100) substrate, compared to the c-cut sapphire substrate. The electrical resistivity decreases monotonously with increase in indium fraction and the alloy films on Si (100) show substantially higher mobility, compared to those on sapphire. These features are attributed to superior crystallinity of alloy films on Si (100), which possibly arise from the formation of interfacial hexagonal α-Si{sub 3}N{sub 4}, owing to the interaction of nitrogen plasma with Si surface.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Effects of confinements on morphology of In{sub x}Ga{sub 1–x}As thin film grown on sub-micron patterned GaAs substrate: Elastoplastic phase field model

An elastoplastic phase field model is developed to investigate the role of lateral confinement on morphology of thin films grown heteroepitaxially on patterned substrates. Parameters of the model are chosen to represent In{sub x}Ga{sub 1-x}As thin films growing on GaAs patterned with SiO₂. We determined the effect of misfit strain on morphology of thin films grown in 0.5 μm patterns with non-uniform deposition flux. Growth of islands inside patterns can be controlled by non-uniformity of deposition flux, misfit strain between film and the substrate, and also strain energy relaxation due to plastic deformation. Our results show that the evolution of island morphology depends non-monotonically on indium content and associated misfit strain due to coupling between the plastic relaxation and the confinements effects. Low indium concentration (0%–40%) causes formation of instabilities with relatively long wavelengths across the width of the pattern. Low surface diffusion (due to low indium concentration) and fewer islands across the pattern (due to small misfit strain) lead to formation and growth of islands near the walls driven by overflow flux. Further increase in indium concentration (40%–75%) increases the lattice mismatch and surface diffusivity of the film, and also activates plastic deformation mechanism, which leads to coalescence of islands usually away from the edges. By further increasing the indium concentration (up to 100%), plastic deformation relaxes most of the strain energy density of the film, which prevents formation of instabilities in the film. Hence, in this case, islands are only formed near the walls.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Communication—Electrodeposition of Indium Directly on Silicon

Direct electrodeposition of indium onto silicon paves the way for advances in microelectronics, photovoltaics, and optoelectronics. Indium is generally electrodeposited onto silicon utilizing a physically or thermally deposited metallic seed layer. Eliminating this layer poses benefits in microelectronics by reducing resistive interfaces and in vapor-liquid-solid conversion to III-V material by allowing direct contact to the single-crystal silicon substrate for epitaxial conversion. We investigated conditions to directly electrodeposit indium onto n-type Si(100). We illustrate that a two-step galvanostatic plating at low temperatures can consistently produce smooth, continuous films of indium over large areas, in bump morphologies, and conformally into inverted pyramids.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗