Sb Films Research Articles

Thermoelectric and Structural Properties of Transparent Sb-Doped ZnO Thin Films Sputtered in a Confocal Geometry

This study focuses on understanding the influence of low Sb doping on ZnO’s electrical, optical, and thermoelectrical properties, while also studying its structural and morphological parameters. For this, several ZnO films with varying Sb target current densities, in the range of 0–0.27 mA/cm2, were produced by DC magnetron sputtering in a confocal geometry. As a result, thin ZnO:Sb films with an average transparency in the visible region greater than 80% are obtained, revealing for optimized conditions an absolute Seebeck coefficient of 100 μV/K and a respective power factor of 1.1 mW∙m−1∙K−2 at 300 K, effectively modifying the electrical, optical, and thermoelectrical properties of the material and ensuring its suitability for heat harvesting applications. From atom probe tomography experiments, a larger Zn content is registered at triple junctions of the grain boundary, which matches the approximately 25 nm crystallite grain size derived from the X-ray diffraction analysis.

Effect of Zn atomic diffusion due to pulsed electric field treatment on the thermoelectric properties of Zn–Sb films

Zn4Sb3 has brought into sharp focus by its low cost and excellent thermoelectric (TE) properties in the medium temperature range. Zn atoms can diffuse in the Zn4Sb3 matrix under the treatment of temperature or current. This provides a way to control its TE performance. In this study, the TE properties of the Zn4Sb3 films were improved by the Zn atomic diffusion under the treatment of periodic pulsed electric field. The Zn atomic diffusion is caused by the electrostatic interaction of the pulsed electric field and the diffusion mode is related to the pulse period. When the pulse period is smaller than 10 s, the interstitial Zn atom diffuses first. The Zn vacancy increases, leading to the increase of the carrier concentration and the decrease of the resistivity. When the pulse period increases to 100 s, more Zn(1) atoms diffuse through the interstitial position, resulting in a small amount of ZnSb phase. Thereby in the Zn4Sb3 films, the carrier concentration decreases and the Seebeck coefficient increases. This kind of the synergistic effect decreases the resistivity and increases the Seebeck coefficient. The power factor of the Zn4Sb3 films treated with a pulse period of 100 s is more than 4500 μW m−1 K−2 in the range of 373 K–573 K. This study presents a new method to control atomic diffusion by periodic pulsed electric field, and the TE properties of the Zn4Sb3 films are improved.

Free-standing [0 0 1]-oriented one-dimensional crystal-structured antimony selenide films for self-powered flexible near-infrared photodetectors

Flexible optoelectronic is one of the key components for acquiring biological signals in wearable devices and implantable systems. Recently, antimony selenide (Sb2Se3) has shown an exciting potential for flexible optoelectronic applications due to its unique one-dimensional (1D) ribbon-typed crystal structure, low-cost constituents, and superior optoelectronic properties. However, the growth of [001]-oriented Sb2Se3 film, which can efficiently enhance the carrier transport, is still challenging, particularly for its application in flexible electronics. Herein, we propose to grow the free-standing [001]-oriented Sb2Se3 film for self-powered flexible photodiode through selenizing the highly (0001)-textured Sb film on mica substrate. The theoretical calculation reveals that Sb(0001) plane provides a high adsorption energy for Se atoms, which promotes the [001]-oriented growth of Sb2Se3 film. The weak vdW interaction between Sb2Se3 film and mica substrate enables the film separation, and results in a free-standing Sb2Se3 film. Benefiting from the enhanced carrier transport in [001]-oriented Sb2Se3 film, the flexible photodiode exhibits a high responsivity up to 0.74 A W−1, a specific detectivity of 5.1 × 1013 Jones, a linear dynamic range of 102 dB, rise/fall time of 0.16/0.15 ms for near-infrared light detection without any external bias, and excellent folding endurance after 1000 bending cycles. It has been also successfully employed as a wearable photodetector to detect a person’s heart rate. This work demonstrates a strategy for the orientation control of low-dimensional crystal-structured materials and a great potential of free-standing films in flexible electronics applications.

Multilevel resistance state tuned by change in crystallization mode of superlattice-like Sb/Si3N4 films

Phase change materials (PCMs) have been attracting increasing interest in computer bionics and artificial intelligence neuron systems. However, the influence of interface between Si3N4 and PCMs on phase chang behavior is still unclear. In this paper, phase change performance and crystallization behavior of homogeneous Sb film are adjusted by changing the thickness of the Si3N4 film and the iteration period. Sb film covered by Si3N4 has better thermal stability, better data retention, and higher crystallization rate due to that the stable Si3N4 can reduce the long-range order and inhibit the nano-size growth of Sb crystal grains. The low element diffusion between Sb and Si3N4 is favorable to stabilize the nano-interface and significantly improve the resistance drift. The resistance polymorphism including high, intermediate, and low resistance states can be obtained by annealing at different temperatures. The ability to achieve such a multilevel resistance state is ascribed to the nucleation-dominated crystallization mode.

Cesium intercalation of graphene: A 2D protective layer on alkali antimonide photocathode

Alkali antimonide photocathodes have wide applications in free-electron lasers and electron cooling. The short lifetime of alkali antimonide photocathodes necessitates frequent replacement of the photocathodes during a beam operation. Furthermore, exposure to mediocre vacuum causes loss of photocathode quantum efficiency due to the chemical reaction with residual gas molecules. Theoretical analyses have shown that covering an alkali antimonide photocathode with a monolayer graphene or hexagonal boron nitride protects it in a coarse vacuum environment due to the inhibition of chemical reactions with residual gas molecules. Alkali antimonide photocathodes require an ultra-high vacuum environment, and depositing a monolayer 2D material on it poses a serious challenge. In the present work, we have incorporated a novel method known as intercalation, in which alkali atoms pass through the defects of a graphene thin film to create a photocathode material underneath. Initially, Sb was deposited on a Si substrate, and a monolayer graphene was transferred on top of the Sb film. Heat cleaning around 550–600 °C effectively removed the Sb oxides, leaving metallic Sb underneath the graphene layer. Depositing Cs on top of a monolayer graphene enabled the intercalation process. Atomic force microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, low energy electron microscopy, and x-ray diffraction measurements were performed to evaluate photocathode formation underneath the monolayer graphene. Our analysis shows that Cs penetrated the graphene and reacted with Sb and formed Cs3Sb.

Morphological & Structural Control of Electrodeposited Sb Anodes through Solution Additives and Their Influence on Electrochemical Performance in Na-Ion Batteries

Alloy-based materials such as antimony (Sb) are of interest for both Li/Na-ion batteries due to their theoretical capacity and electronic conductivity. Of the various ways to fabricate Sb films (slurry casting, sputtering, etc.) one promising route is through the use of electrodeposition. Electrodeposition is an industrially relevant synthetic technique that allows for the use of solution additives to control different characteristics such as film uniformity, morphology, and electrical conductivity. Solution additives such as cetyltrimethylammonium bromide (CTAB) and bis-(3-sulfopropyl) disulfide (SPS) have been used to control characteristics such as particle morphology, and electrical conductivity in various applications but have not been applied to the electrodeposition of Sb for battery applications. In this study, Sb films were electrodeposited with various concentrations of CTAB and SPS and the structure, morphology, composition, and electrochemical performance in Na-ion batteries were compared. We report that CTAB and SPS additives can significantly influence electrodeposited Sb films by altering the morphology and reducing the crystallinity of the Sb films, affecting the electrochemical performance. These studies provide valuable insight into the tunability of alloy-based films through electrodeposition and solution additives.

Investigation on electrochemical deposition of Sb2Se3 thin films in aqueous acidic medium

• Thin films of Sb 2 Se 3 have been synthesized by electro-deposition method. • Bath pH and applied potential have a sizable effect on the films quality. • Annealing process is required to control the crystallization of Sb2Se3 thin films. • The suitable band gap of 1.23 eV for the solar cells is reached. Antimony selenide (Sb 2 Se 3 ) thin films were deposited on tin oxide coated glass substrates by potentiostatic electrodeposition from an acidic aqueous bath for 30 min followed by the annealing process in a tube furnace at 350 °C for 10 min under nitrogen atmosphere. The aim of this work is to investigate the effect of the bath solution's pH and the applied potential on the structural, morphological, compositional and optical properties of Sb 2 Se 3 thin films. The optimal deposition conditions and bath acidity were identified to produce good quality Sb 2 Se 3 films suitable for applications in terms of composition, crystallinity, morphology and band gap.

Electrocatalytic CO2 reduction reaction over group 15 bismuth and antimony film electrodes: What makes difference?

Electrocatalytic CO2 reduction reaction (EC CO2 RR) activities and products are known to be highly dependent on the nature of electrode materials. Herein, Bi and Sb (in group 15 with n-1d10ns2np3) electrodes were chosen and evaluated for EC CO2 RR under various conditions of different applied potentials, electrolytes, concentration, and UV light. Major products were observed to be formate and H2, and minor products included CO. Bi film electrode showed high Faradaic efficiency (FE) of ~94% and the selectivity of 95% for formate. Overlayer vanadium on Bi further enhanced the FE of formate. However, Sb film exhibited much higher FE of H2 than that of formate. UV light was observed to promote formate and CO productions. The FEs of formate and H2 were discussed with exposed crystal facets and density of states near the Fermi level. The very unique detailed study provides valuable information on the development of Bi and Sb-based electrodes for EC CO2 RR of producing value-added carbon products.

Emergent and Tunable Topological Surface States in Complementary Sb/Bi2Te3 and Bi2Te3/Sb Thin-Film Heterostructures.

Epitaxial thin-film heterostructures offer a versatile platform for realizing topological surface states (TSSs) that may be emergent and/or tunable by tailoring the atomic layering in the heterostructures. Here, as an experimental demonstration, Sb and Bi2Te3 thin films with closely matched in-plane lattice constants are chosen to form two complementary heterostructures: Sb overlayers on Bi2Te3 (Sb/Bi2Te3) and Bi2Te3 overlayers on Sb (Bi2Te3/Sb), with the overlayer thickness as a tuning parameter. In the bulk form, Sb (a semimetal) and Bi2Te3 (an insulator) both host TSSs with the same topological order but substantially different decay lengths and dispersions, whereas ultrathin Sb and Bi2Te3 films by themselves are fully gapped trivial insulators. Angle-resolved photoemission band mappings, aided by theoretical calculations, confirm the formation of emergent TSSs in both heterostructures. The energy position of the topological Dirac point varies as a function of overlayer thickness, but the variation is non-monotonic, indicating nontrivial effects in the formation of topological heterostructure systems. The results illustrate the rich physics of engineered composite topological systems that may be exploited for nanoscale spintronics applications.

Band structure of free Sb layers and spin-orbit splitting of surface bands

As follows from performed DFT calculations, a semimetal state of the bulk Sb crystal results from a spontaneous coupling of neighboring layers. The related decrease of DOS in vicinity of Fermi level, in turn, may be considered as the driving force of the coupling and formation of the characteristic bilayer structure of Sb crystal. The same mechanism of structural transformations is pertinent also to Sb films, built from several hexagonal monolayers. In particular, the coupling leads to semimetallic properties of films built from even number of Sb(111) monolayers, while the films with an odd number of monolayers are strongly metallic, with a high density of states at Fermi level. This feature can be used to control the surface electronic structure by deposition of the proper number of Sb monolayers onto appropriate substrate. Hydrogen monolayer on one face of the Sb(111) film leads to the spin-orbit splitting of the bands.

Flexible elemental thermoelectrics with ultra-high power density

Flexible thermoelectrics have attracted great attention due to their potential to convert waste heat to electricity to power wearable devices and IoT (Internet of things) sensors. Though organic thin-film thermoelectric materials are popular choice for preparing flexible thermoelectrics, they suffer from low thermoelectric performances due to the low figure of merit zT. In this work, we demonstrate a new strategy to design high-performance thermoelectrics by highlighting the influence of power factors instead of zT. To verify our claim, thermoelectric is prepared through sputtering high-power factor but low zT elemental thin films of Sb (p-type) and Ni (n-type) on a polyimide substrate. In this system, ascribed by the high-power factor (up to 7 mW/mK2), a high power density of up to 4.7 mW/cm2 at a temperature gradient of 50 K can be achieved, even with the low zT (<0.1). In addition, finite element method (FEM) analysis shows that the benefit of high-power factor increases with decreasing film thicknesses. Our results show that in the case of organics and inorganics thin films, maximizing power factor is more important than maximizing zT. This finding serves to guide the design paradigm of thermoelectrics for wearable devices and is useful for the broad organic electronics community.

Structure of Strained Low‐Dimensional Sb by In Situ Surface X‐Ray Diffraction

Antimony ultrathin films in tensile strain are grown on InAs(111)B substrates and studied in situ using surface X‐ray diffraction. The detailed atomic structures of two highly crystalline Sb(0001) films are derived, with thicknesses of 19 and 4 bilayers. Features considered in structural modeling include interfacial intermixing, surface roughness, individual layer relaxations, and rotational twin domains (RTDs). The four‐bilayer film shows significant structural relaxation in every layer, while both films include RTDs. The results are discussed in relation to the topological properties of low‐dimensional Sb.

Electrical and magnetotransport properties of In0.95Mn0.05Sb film

The In0.95Mn0.05Sb film has been obtained on a Silicon substrate using a thermally evaporated technique. The structural, electrical, magnetotransport and surface magnetic interaction properties of the Mn-doped InSb film are investigated. The X-ray diffractogram shows a single-phase nanocrystalline structure in the highly oriented direction of (111). The upturn in the resistivity observed at (<35 K) low temperature is attributed to the Coulomb Blockade effect. From the resistivity measurement, the observed bandgap is 0.16 eV. At room temperature, negative magnetoresistance is observed. The weak magnetic signals at the surface are observed through magnetic force microscopy.

Growth and characterization of quaternary-alloy ferromagnetic semiconductor (In,Ga,Fe)Sb

We study the growth and properties of the quaternary-alloy ferromagnetic semiconductor (In0.94−x,Gax,Fe0.06)Sb (x = 5%–30%; the Fe concentration is fixed at 6%) grown by low-temperature molecular beam epitaxy. Reflection high-energy electron diffraction patterns, scanning transmission electron microscopy lattice images, and x-ray diffraction spectra indicate that the (In0.94−x,Gax,Fe0.06)Sb layers have a zinc blende crystal structure without any other second phase. The lattice constant of the (In0.94−x,Gax,Fe0.06)Sb films changes linearly with the Ga concentration x, indicating that Ga atoms substitute In atoms in the zinc-blende structure. We found that the carrier type of (In0.94−x,Gax,Fe0.06)Sb can be systematically controlled by varying x, being n-type when x ≤ 10% and p-type when x ≥ 20%. Characterization studies using magnetic circular dichroism spectroscopy indicate that the (In0.94−x,Gax,Fe0.06)Sb layers have intrinsic ferromagnetism with relatively high Curie temperatures (TC = 40–120 K). The ability to widely control the fundamental material properties (lattice constant, bandgap, carrier type, and magnetic property) of (In0.94−x,Gax,Fe0.06)Sb demonstrated in this work is essential for spintronic device applications.

Simultaneously higher thermal stability and lower resistance drifting for Sb/In48.9Sb15.5Te35.6 nanocomposite multilayer films

In this study, In48.9Sb15.5Te35.6 (IST) was introduced as a stable interlayer to improve the weak amorphous thermal stability and large resistance drift of Sb films.

Электронная микроскопия микроструктуры тонких пленок сурьмы переменной толщины

Thin Sb films with a thickness gradient deposited in vacuum were investigated by transmission electron microscopy. Microstructures in films with increasing thickness change from amorphous islands of increasing density and size to labyrinthine and continuous films with texturing, which also changes with increasing thickness. Based on the analysis of the patterns of bend extinction contours, a strong internal bending of the crystal lattice, up to 120 deg/μm, and the dependence of the crystallographic orientations in the structures of the film on the thickness were revealed.

Electron microscopy of the microstructure of antimony thin films of variable thickness

Thin Sb films with a thickness gradient deposited in vacuum were investigated by transmission electron microscopy. Microstructures in films with increasing thickness change from amorphous islands of increasing density and size to labyrinthine and continuous films with texturing, which also changes with increasing thickness. Based on the analysis of the patterns of bend extinction contours, a strong internal bending of the crystal lattice, up to 120 deg/μm, and the dependence of the crystallographic orientations in the structures of the film on the thickness were revealed. Keywords: Antimony, thin films, TEM, crystallography, extinction bend contours.

Nano-composite phase-change antimony thin film for fast and persistent memory operations

Elemental Sb phase-change material (PCM) has to be diminished to nanometer in thickness to guarantee non-volatile memory storage. Integrating ultrathin Sb films poses great challenges in manufacturing high-density phase-change random-access memory (PCRAM) chips. Here, we introduce another feasible approach of utilizing nano-composite Sb–SiO2 PCM, for which we demonstrate superior phase-change properties of faster crystallization speed and better data retention ability over the conventional Ge2Sb2Te5 compound. These two seemingly conflicting features of the Sb–SiO2 are reconciled by an obvious fragile-to-strong crossover in crystallization kinetics of the supercooled Sb liquids via nanosize confinements, enabling the more suffocated atomic diffusion near room temperature and the comparable crystal growth at elevated temperatures to the Ge2Sb2Te5. The nanosize confinements also catalyze heterogeneous nucleation remarkably, therefore speeding up the SET operation of the Sb–SiO2-based PCRAM device by over two orders of magnitude as compared to the Ge2Sb2Te5-based one. In addition, owning the potentials to accomplish low-drift and long-life memory programming, the nano-composite Sb–SiO2 PCMs hold great promise to be employed for working memory and neuromorphic computing applications.

Natural dye solar cell: Conductive transparent oxide, photo anode, sensitizers, electrolyte, and γ-radiation response

ABSTRACT This article represents the gamma irradiation effects on the experimental details of prepared natural dye solar cell (NDSC) components. The optical absorption and physical characteristics of NDSC components were investigated by using different techniques such as Fourier Transform Infrared, Electron Paramagnetic Resonance, Scanning Electron Microscope, and UV−Vis absorption Spectroscopy. The average optical energy gap of the natural fruit dyes was found 2.1 ± 0.3 eV. The transmittance onset of conductive transparent oxide was blue shifted with the increase of gamma dose. Optical energy gap of the electrolyte was calculated to have a value of 2.61 eV. The maximum peaks of incident photon to current efficiency spectrum were found for SnO2 (undoped) film at 515 nm and for SnO2:Sb (doped) film at 550 nm. The short current and open voltage were found to be 0.92 mA and 0.44 V, respectively, for doped film.

Structural and electrical properties of epitaxial SnO2: Sb films deposited on 6 H-SiC by MOCVD

Structural and electrical properties of epitaxial SnO2: Sb films deposited on 6 H-SiC by MOCVD