Sb Films Research Articles

Topological states of Sb thin films contacted by a single sheet of heterogeneous atoms

We found that thin antimony films contacted by a single layer of a variety of atoms can form topological surface and interface states in the gap of bulk energy bands that preserve time-reversal symmetry. Using density functional calculation, we have included bismuth, graphene, boron-nitride and boron-doped graphene layers in our investigation. In most cases, Dirac cones are found in the band structures and spin textures indicate no back scattering of conduction electrons. In the case of a BC3 layer deposited on an Sb film as thin as three bilayers, a Dirac cone consisting mostly of interface states is formed close to the Fermi level. If the composite is gated by an adjustable voltage, electron transport can switch between two modes of opposite spins, and between one or two modes of 100% spin polarization. The results should be very useful in the applications of topological conduction and spintronics.

Semimetal-semiconductor transitions in bismuth-antimony films and nanowires induced by size quantization

In this paper we present the experimental results of an investigation of the electrical transport, thermoelectrical properties, the Shubnikov de Haas oscillations of Bi1 − xSbx films (0 600 nm show that overlapping of L and T bands was twice smaller than that in pure Bi. The temperature dependences of thin semimetalic Bi-3 at % Sb films and Bi-2 at % Sb wires show a semiconducting behavior. The semimetal-semiconductor transition induced by the quantum confinement effect is observed in semimetal Bi1 − xSbx films and nanowires at the diameters up to five times greater than those in the pure Bi. That experimental fact, on the one hand, will allow observing the display quantum confinement effect at higher temperatures on nanowires of the same diameters, and, on the other hand, will allows separating effects connected with the surface state and the quantum size effects. In addition, the thermoelectric properties and thermoelectric efficiency of bismuth-antimony wires are considered and a possibility to use them in thermoelectric converters of energy is discussed.

Free‐Standing, Single‐Crystalline Parallelogram Sb Shallow‐Doped ZnO Wave‐Guided Optical Resonators

Single‐crystalline Sb shallow‐doped ZnO microwire wave‐guided optical resonators are synthesized via a simple carbothermal reduction method. The formation of the ZnO wave‐guided microcavities are investigated systematically, and the Sb film formed on the substrate is confirmed to be the critical factor in crystal growth. The optical signals of the annealed ZnO microcavities induced by the Sb related acceptor defects are clarified through a low‐temperature spectrum detection technology. Excitation power and temperature dependence of UV lasing properties of the ZnO microcavities annealed in different atmospheres are studied. The results reveal that such high‐quality Sb shallow‐doped ZnO wave‐guided microcavities have excellent optical responses and a strong light‐field regulation capability, which would greatly promote the development of ZnO cavity‐based photoelectronic devices.

Dual-acceptor doped p -ZnO:(As,Sb)/n -GaN heterojunctions grown by PA-MBE as a spectrum selective ultraviolet photodetector

High quality heterojunctions based on dual acceptor doped ZnO:(As,Sb) films grown on n-type GaN templates were used for UV detector application. Photodetectors made on the obtained diodes appeared to have a high selectivity in the UV spectral range. Photocurrent measurements revealed a very narrow response window of ∼12 nm only. The difference between the dark and bright current was large and the ratio of these currents was about 103. The response time of the detectors is shorter than 1 ms.

PA-MBE Grown p-n (p-ZnO:(As+Sb)/<i>n</i>-GaN) and p-i-n (p-ZnO:As/HfO<sub>2</sub>/n-GaN) Heterojunctions as a Highly Selective UV Detectors

Zinc oxide is a promising candidate for application in UV photodetectors due to the large direct band gap and the high absorption coefficient in the UV. The high quality p-n and p-i-n structures consist of single or dual acceptor doped ZnO:(As,Sb) films grown by MBE, thin HfO2 layer grown by ALD method and n-type GaN templates. The As and Sb concentrations is 1020 cm-3.The maximum forward-to-reverse current ratio IF/IR in the obtained p-n diodes is of about 105 at ±4 V and in the case of p-i-n diodes is of about 106, which are very good results for this type of heterojunctions. The UV photodetectors are highly selective. The maximum of the detection wavelength was found at about 365 nm (FWHM of the photocurrent peak is ~17 nm). In the case of p-i-n detectors, the maximum of detection was found at 376, 360, and 341 nm. Additionally, it is possible to control the detection range by the applied reverse voltage. The dark to light current ratio in both cases is ~104.

Study of Sb/SnO2 bi-layer films prepared by ion beam sputtering deposition technique

In the present work, bi-layer thin films of Sb/SnO2 were produced on unheated glass substrates using ion beam sputtering (IBS) technique without post annealing treatment. The thickness of Sb layers was varied from 2 to 10nm and the Sb layers were deposited on SnO2 layers having thicknesses of 40nm to 115nm. The effect of thickness was studied on the morphological, electrical and optical properties. The Sb/SnO2 bi-layer resulted in lowering the electrical resistivity as well as reducing the optical transmittance. However, the optical and electrical properties of the bi-layer films were mainly influenced by the thickness of Sb layers due to progressive transfer in structures from aggregate to continuous films. The bi-layer films show the electrical resistivity of 1.4×10−3Ωcm and an optical transmittance of 26% for Sb film having 10nm thickness.

Preferential Orientation and Surface Oxidation Control in Reactively Sputter Deposited Nanocrystalline SnO2:Sb Films: Electrochemical and Optical Results

Antimony doped tin oxide is a versatile transparent electrical conductor. Many of its properties depend on the electronic band structure at the surface of a thin film–such as the position of the Fermi level, ionization potential Ip, optical gap energy, etc.–which in its turn is related to the surface termination given by the crystallographic orientation of the film. We prepared SnO2:Sb films by reactive DC magnetron sputtering at different oxygen/argon ratios and found by X-ray diffraction that the crystallographic orientation could be changed from tetragonal (101) to tetragonal (110) as the oxygen content was raised. Electrochemical measurements showed that this change in preferential orientation was accompanied by an increase of Ip by more than 1 eV as a result of the modification of the oxidation state of tin atoms at the film's surface. Such alterations of Ip have a large impact on the electrochemical, photocatalytic and gas sensing behavior of the material. Moreover, preferential orientation control–and hence Ip tuning–allow the tailoring of SnO2:Sb electrodes for various application by reducing the Schottky barrier.

Electrodeposited antimony and antimony–gold nanocomposite modified carbon paste electrodes for the determination of heavy metal ions

Sb film modified carbon paste electrode (CPE) for the determination of Cd and Pb and Sb/Au composite material for the determination of Hg. Stripping plot of Cd and Pb using Sb film modified CPE and the stripping plot of Hg using Sb/Au composite modified CPE are shown along with the SEM image of the Sb/Au composite material.

Topological phase transitions in Sb(111) films driven by external strain and electric field

Using the first-principles calculations, we systematically study the lattice structure and topological phase transitions driven by external strain and electric field in Sb(111) thin films. The results show that 1-bilayer film is a robust trivial semiconductor, and the band gap of a 4-bilayer film can be tuned by strain but without gap closing up to strains of 8%, indicating a robust two-dimensional topological insulator. However, for the remaining bilayers below 9 bilayers, the topological phase transitions are driven if a suitable value of strain is applied. Moreover, the electric field not only can induce the Rashba splitting, but also may induce the gap closing at other points rather than at time-reversal invariant momenta. Our theoretical results provide efficient methods to manipulate topological phase transitions of Sb films.

Effect of Sb doping on structural, electrical and optical properties of epitaxial SnO2 films grown on r-cut sapphire

Abstract Antimony-doped tin oxide (SnO 2 :Sb) films have been epitaxially grown on r-cut sapphire substrates by metalorganic chemical vapor deposition (MOCVD). Although the films were all (1 0 1) oriented with rutile structure, they showed different microstructure, electrical and optical properties as Sb doping varied from 0% to 7%. The doping of Sb could reduce the formation of (1 0 1) twins in SnO 2 films. The SnO 2 :Sb film with the lowest resistivity of 1.3 × 10 −3 Ω cm and the highest carrier concentration of 2.5 × 10 20 cm −3 was obtained at 5% Sb-doping. The undoped and Sb-doped SnO 2 films exhibited different electrical transport mechanism. The samples showed high transparency of ∼80% in the visible range. As Sb concentration increased, the absorption edge of the films shifted to shorter wavelength and the calculated optical band gaps were about 3.77–4.11 eV.

Fiber-like stripe ATO (SnO2:Sb) nanostructured thin films grown by sol–gel method: Optical, topographical and electrical properties

Abstract Sb-doped SnO 2 thin films were deposited on glass substrates by sol–gel dip coating technique. The effects of dopant concentration on structural, morphological, electrical, and optical properties of ATO thin films were investigated. The compositional analysis of the films carried out by using EDX and XPS. The analyses confirmed the presence of Sb in SnO 2 thin films. The XRD results showed a tetragonal rutile structure of SnO 2 and the crystallite size of the films decreased with increasing dopant concentration. The surface morphology of the films is found to depend on the doping concentration. The wrinkle network with uniformly protruding fiber like stripes arranged randomly on the film surface can be observed at a higher Sb content (above 7 mol%). The surface topographical image exhibited that the surface roughness of films increased by Sb doping. A minimum resistivity of 1.72 × 10 −2 Ω cm was obtained for the ATO (10 mol% Sb) film. The Hall mobility of the ATO films decreased with increasing the Sb concentration. The optical study revealed that transmittance of the films was diminished by doping and also a gradual increase in the optical band gap was observed by enhancement of dopant concentration. The compositional dependence of optical parameters such as refractive index, extinction coefficient, dispersion energy, real and imaginary parts of the dielectric constant and optical conductivity were also investigated. The PL measurements illustrated the photoluminescence quenching with increasing Sb content up to 10 mol%.

Structural, morphological and electronic study of CVD SnO2:Sb films

We have prepared solid thin film samples of SnO2:Sb in different ratios using atmospheric pressure chemical vapour deposition technique APCVD. The chemical composition was determined with Rutherford Backscattering Spectroscopy (RBS) within an error of 1%. X-ray diffraction was used to study the influence of Sb concentration on the lattice parameters and preferred orientations. We have found that sample of concentration 4% showed a (200) preferred orientation. The AFM and SEM images showed that the surface roughness of our samples was influenced by the doping concentrations. The lowest electrical surface resistance was 8.0 Ω □−1 for a 3% concentration sample. We found that the contribution to the metallic state is influenced by oxygen vacancy and Sb doping. Also, the sample of good electrical conductive property has an optical gap of 3.60 eV band at room temperature.

Topological surface states revealed by Sb thin films adsorbed with impurity atoms

The prevalent concept is that a topological insulator is made of thick layers of atoms so that its surfaces, where electrical conduction occurs, can be distinguished from the insulating bulk of the interior. One important reason is that the thin film topological insulator may cause the opening of energy band gaps by quantum tunneling between the two surfaces. Inspired by an experiment on antimony thin films, we use density functional calculations to investigate the electronic structure of the four-bilayer Sb film and find that adsorptions of nonmagnetic impurity atoms of hydrogen and 3$d$ transition-metal atoms on the film all close the energy gap of the free-standing film and facilitate the formation of Dirac cones that preserve time-reversal symmetry. However, magnetic atoms of the 3$d$ transition metals do just the opposite. The results suggest the counterintuitive concept of achieving topological conduction by doping nonmagnetic impurity atoms on thin films of topological insulators.

Microstructure and physical properties of sol gel derived SnO2:Sb thin films for optoelectronic applications

Antimony doped tin oxide thin films were deposited on glass substrates by sol-gel dip coating technique. X-ray diffraction pattern showed the deterioration of the crystallinity of the films with increase in antimony doping concentration. Atomic force microscopy studies showed an inhibition of grain growth with increase in Sb concentration.The rms roughness value of SnO2:Sb thin films are found to 1% of film thickness which makes them suitable for optoelectronic applications. The film surface revealed positive skewness and high kurtosis values which make them favorable for tribological applications. The lowest resistivity (about10−5Ωm) was obtained for the 5mol% Sb doped SnO2: Sb films. These films acquire n-type conductivity due to non- stoichiometry (oxygen vacancies and interstitial tin atoms) and by the addition of Sb. The optical properties of the films have been studied from transmission spectra. An average transmittance of >80% (in UV–vis region) was observed for all the films. Optical band gap energy of SnO2:Sb films were found to vary in the range of 3.69–3.97eV with the increase in Sb doping concentration. Photoluminescence spectra of the films exhibited an increase in the emission intensity with increase in antimony doping concentration which is due the combined effect of charge balance and decrease in grain size. The enhancement of PL intensity in the antimony doped SnO2 thin films make it suitable for generation of solid state lighting in light emitting diode.

Epitaxial growth of Sb-doped nonpolar a-plane ZnO thin films on r-plane sapphire substrates by RF magnetron sputtering

► Sb-doped nonpolar a -plane ZnO layers were epitaxially grown on sapphire substrates. ► Crystallinity and electrical properties were studied upon growth condition and doping concentration. ► The out-of-plane lattice spacing of ZnO films reduces monotonically with increasing Sb doping level. ► The p-type conductivity of ZnO:Sb film is closely correlated with annealing condition and Sb doping level. In this study, the epitaxial growth of Sb-doped nonpolar a -plane ( 1 1 2 ¯ 0 ) ZnO thin films on r -plane ( 1 1 ¯ 0 2 ) sapphire substrates was performed by radio-frequency magnetron sputtering. The influence of the sputter deposition conditions and Sb doping concentration on the microstructural and electrical properties of Sb-doped ZnO epitaxial films was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and the Hall-effect measurement. The measurement of the XRD phi-scan indicated that the epitaxial relationship between the ZnO:Sb layer and sapphire substrate was 1 1 2 ¯ 0 ZnO / / ( 1 1 ¯ 0 2 ) Al 2 O 3 and 1 1 ¯ 0 0 ZnO / / 1 1 2 ¯ 0 Al 2 O 3 . The out-of-plane a -axis lattice parameter of ZnO films was reduced monotonically with the increasing Sb doping level. The cross-sectional transmission electron microscopy (XTEM) observation confirmed the absence of any significant antimony oxide phase segregation across the thickness of the Sb-doped ZnO epitaxial film. However, the epitaxial quality of the films deteriorated as the level of Sb dopant increased. The electrical properties of ZnO:Sb film are closely correlated with post-annealing conditions and Sb doping concentrations.

Electrodeposition of Antimony, Tellurium and Their Alloys from Molten Acetamide Mixtures

We examine the electrodeposition of antimony (Sb), tellurium (Te) and their alloys from molten mixtures of acetamide - antimony chloride and tellurium chloride. The binary mixtures of acetamide with SbCl3 and TeCl4 exhibit eutectic formation with large depressions of freezing points to below room temperature. At temperatures up to 100 °C, these mixtures are highly conductive and can be used to deposit elementary Sb and Te films at current density up to 7 A dm− 2. Antimony telluride alloy films with composition between 20 and 81 at.% Te are obtained from ternary mixtures containing up to 0.48 M SbCl3 and up to 0.12 M TeCl4. Composition of the antimony telluride films can be controlled by adjusting bath composition and current density.

Magnetic behaviour and DCEMS study of SnO2 films implanted with 57Fe

Fe implanted SnO2 films (5 × 1016 and 1 × 101757Fe ions/cm2) characterized by conversion electron Mossbauer spectroscopy (CEMS) are reviewed. The substrate temperatures affect the growth of precipitated iron oxides. The Fe ion implanted film at room temperature (RT) shows no Kerr effect and no magnetic sextet in CEM spectra. The SnO2 film implanted with 57Fe at the substrate temperature of 300 °C show a small Kerr effect although the magnetic sextet is not observed, but post-annealing results in the disappearance of the Kerr effect. This magnetism is considered to be due to defect induced magnetism. Some samples were measured by CEMS at 15 K. SnO2 (0.1 at %Sb and 3 at %Sb) films, implanted at 500 °C and the post-annealed samples, show RT ferromagnetism due to formation of clusters of magnetite and maghemite, respectively. The layer by layer analysis of these films within 100 nm in thickness has been done by depth sensitive CEMS (DCEMS) using a He + 5 % CH4 gas counter. The structures and compositions of Fe implanted SnO2 films, and the effects due to post-annealing were investigated.

Competing Weak Localization and Weak Antilocalization in Ultrathin Topological Insulators

We demonstrate evidence of a surface gap opening in topological insulator (TI) thin films of (Bi(0.57)Sb(0.43))(2)Te(3) below six quintuple layers through transport and scanning tunneling spectroscopy measurements. By effective tuning the Fermi level via gate-voltage control, we unveil a striking competition between weak localization and weak antilocalization at low magnetic fields in nonmagnetic ultrathin films, possibly owing to the change of the net Berry phase. Furthermore, when the Fermi level is swept into the surface gap of ultrathin samples, the overall unitary behaviors are revealed at higher magnetic fields, which are in contrast to the pure WAL signals obtained in thicker films. Our findings show an exotic phenomenon characterizing the gapped TI surface states and point to the future realization of quantum spin Hall effect and dissipationless TI-based applications.

Antimony-Doped Tin(II) Sulfide Thin Films

Thin-film solar cells made from earth-abundant, inexpensive, and nontoxic materials are needed to replace the current technologies whose widespread use is limited by their use of scarce, costly, and toxic elements.(1) Tin monosulfide (SnS) is a promising candidate for making absorber layers in scalable, inexpensive, and nontoxic solar cells. SnS has always been observed to be a p-type semiconductor. Doping SnS to form an n-type semiconductor would permit the construction of solar cells with p-n homojunctions. This paper reports doping SnS films with antimony, a potential n-type dopant. Small amounts of antimony (∼1%) were found to greatly increase the electrical resistance of the SnS. The resulting intrinsic SnS(Sb) films could be used for the insulating layer in a p-i-n design for solar cells. Higher concentrations (∼5%) of antimony did not convert the SnS(Sb) to low-resistivity n-type conductivity, but instead the films retain such a high resistance that the conductivity type could not be determined. Ex...

The influence of annealing atmosphere on the formation and characteristics of microvoid WO3–Sb films

WO3–Sb thin films with and without Sb doping were prepared by the sol–gel spin-coating method. The surface morphology, crystal structure, and binding energy of the WO3–Sb films were investigated before and after annealing under O2 or N2 atmospheres. After spin-coating, Sb2O3 precipitates on the surface of the as-deposited amorphous WO3 films with different Sb/W molar ratios. After annealing in O2 or N2 ambients, the precipitates start to disappear and then microvoids appear on the surface of the crystalline WO3 films with 5% and 10% molar ratios of Sb. WO3–Sb thin films present the monoclinic phase after annealing at 700°C in N2, whereas films show the tetragonal phase after annealing at the same temperature in O2. In addition, Sb segregation occurs on the surface of the WO3 films with Sb additives after annealing at 700°C in N2 ambient. This study discusses the connection among the Sb additive of the WO3–Sb films and how they are influenced by the Sb/W molar ratios and the annealing atmospheres of WO3–Sb films.