Sb Films Research Articles

Iodization of antimony thin films: XRD, SEM and optical studies of nanostructured SbI 3

Antimony films of thicknesses of 25, 40 and 80 nm deposited using thermal evaporation technique were annealed at 200 °C for 6 h. Programmed iodization was carried out at room temperature for periods ranging from 5 min to 9 h on both as-deposited and annealed films. X-ray diffraction studies on iodized films reveal that antimony tri-iodide nanoparticles grow only on annealed antimony films. Surface morphology as revealed through SEM consists of antimony and antimony tri-iodide nanoparticles are 25 nm and 1 μm, respectively. Optical absorption of Sb and SbI 3 nanoparticles carried out at room temperature. As-deposited antimony film of thickness 25 nm exhibits a sharp rise in the absorption near ultraviolet region while post-deposition annealed films were characterized by red shifted absorption. Interestingly 45 nm thick Sb films exhibit a broad volume plasmon resonance peak around 500 nm with a width of 200 nm. Progressive iodization of 25 nm thick film reveals two absorption bands at 381.7 nm (A 2) and 458.3 nm (B 3) with photon energies 3.25 and 2.70 eV, respectively, due to the development of SbI 3 valence band structure. Last members of hydrogen-like series of absorption levels A 2 and B 3 due to halogen doublet (3/2, 1/2) splitting have been observed at room temperature.

Structural characterization and electrical properties of quaternary CdGaInSe 4 thin films

Stoichiometric bulk ingot material of the quaternary CdGaInSe 4 was prepared by direct fusion of the constituent elements in vacuum-sealed silica tubes. Nearly stoichiometric films could be deposited by thermal evaporation of the ingot material in 10 −3 Pa vacuum at a deposition rate 1.5 nm/s. Crystal structure investigation was carried out using X-ray diffractometry and transmission electron diffraction. Elemental composition was determined by means of energy-dispersive X-ray spectrometry. CdGaInSe 4 possesses a tetragonal defective chalcopyrite structure (space group I ¯ 4 ) with lattice parameters a=0.5665 nm and c=1.1221 nm. All the films exhibited n-type conduction and ohmic behaviour with metallic films of Au, Cd, In, Ag and Sb. However, in the case of Al a nonlinear behaviour occurs. Analysis of the temperature dependence of the dark conductivity in the range 130–470 K has revealed three operating conduction mechanisms; a variable range hopping conduction process dominating at low temperatures below 270 K, followed by a transport of the charge carriers across intercrystalline barriers and grain boundaries in the temperature range 270–353 K, and finally an extrinsic conduction above 353 K.

Effects of oxygen concentration on the properties of sputtered SnO2:Sb films deposited at low temperature

Antimony doped tin oxide (SnO2:Sb) films have been prepared by d.c. magnetron sputtering and the properties of the films depend on deposition conditions, such as O2 gas ratio, were investigated. The gas composition was found to affect the properties of the films. With the incorporation additional oxygen, the electrical and optical properties of films significantly improved. The minimum value of resistivity of the films was 4.9×10−3 Ω cm at the oxygen concentration of 30% and the optical transmittance was over 80%.

Influence of magnetic clusters on electrical and magnetic properties of In 1− xMn xSb/GaAs dilute magnetic semiconductor grown by liquid phase epitaxy

In 1− x Mn x Sb films have been grown with different Mn doping concentrations ( x = 0.0085 , 0.018, 0.029 and 0.04) beyond the equilibrium solubility limit by liquid phase epitaxy. We have studied temperature dependent resistivity, the Hall effect, magnetoresistance and magnetization for all compositions. Saturation in magnetization observed even at room temperature suggests the existence of ferromagnetic clusters in the film which has been verified by scanning electron microscopy studies. The anomalous Hall coefficient is found to be negative. Remnant field present on the surface of the clusters seems to affect the anomalous Hall effect at very low fields (below 350 Gauss). In the zero field resistivity, a variable-range hopping conduction mechanism dominates below 3.5 K for all samples above which activated behavior is predominant. The temperature dependence of the magnetization measurement shows a magnetic ordering below 10 K which is consistent with electrical measurements.

BSb films: Synthesis and characterization

BSb films were deposited onto fused silica substrates by coevaporating B and Sb from appropriate boats. Optical studies indicated an indirect band gap of ∼0.59 eV. The films thus prepared were characterized by measuring X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) studies. XPS studies indicated the ratio of B:Sb ∼1. XRD indicated the reflections from (1 0 1), (1 1 1), (1 1 2), (3 3 0), (3 3 1) and (3 2 3) planes of zinc blende BSb. FTIR spectra indicated the peaks for B–B, B–O, B–Sb vibration modes. A strong peak located at ∼151 cm −1 for B–Sb modes dominated the Raman spectra. Electrical resistivity was measured for B–Sb films in the temperature range of 100–353 K. Electron transport process was seen to be governed by Mott's hopping when complete temperature dependence of the conductivity is considered.

Growth and Characterization of Co-Doped Fluorine and Antimony in Tin Oxide Thin Films Obtained by Ultrasonic Spray Pyrolysis

Fluorine (F)-doped, antimony (Sb)-doped, fluorine and antimony co-doped tin oxide (SnO2) thin films were prepared by ultrasonic spray pyrolysis technique using SnCl2, NH4F and SbCl3 as precursors of Sn, F and Sb elements respectively. F and Sb doping concentrations carried out from 1 to 20 wt% and 1 to 4 wt% in F-doped and Sb-doped SnO2 films respectively. In F and Sb co-doped SnO2 films, the proportions of F and Sb to Sn in starting solution were 15 and 2 wt% respectively. XRD patterns showed that the preferred orientation of SnO2:F, SnO2:Sb and SnO2:F, Sb is dependent on the doping concentration. The variation of doping concentration and preferred orientation of the films was reflected in their morphology as investigated by SEM. The electrical properties of the films were performed by Hall effect measurements in van der Pauw configuration. The minimum resistivity values of SnO2:F and SnO2:Sb were found in the films doped with 15 wt% of F and 2 wt% of Sb. However, The minimum of resistivity value of F and Sb co-doped SnO2 films is not better than neither the one of F-doped nor the one of Sb-doped SnO2 films. The optical transmission of SnO2:F films was found to increase with increasing in F doping concentration. Whereas the optical transmission of SnO2:Sb was found to decrease with increasing in Sb concentration. The F and Sb co-doped SnO2 films annealed in three different conditions at 500°C show the lower transmission values than the value obtained in the as-prepared SnO2:F, Sb films.

Structural and photoluminescence properties for SnO2:Sb films prepared on Al2O3 substrate

The SnO2:Sb films have been prepared on sapphire (0001) substrates by radio frequency magnetron sputtering method. The structural and photoluminescence (PL) properties of the films were investigated. The prepared samples are polycrystalline films with rutile structure of pure SnO2. The photoluminescence of the samples was measured at room temperature. An ultraviolet luminescence peak near 334 nm was observed for the first time and the corresponding PL mechanism was investigated.

Deposition of Controlled Thickness Ultrathin SnO<SUB>2</SUB>:Sb Films by Spin-Coating

The technological interest in transparent conductive oxide films (TCOs) has motivated several works in processing techniques, in order to obtain adequate routes to application. In this way, this work describes a new route to obtain antimony-doped tin oxide (ATO) films, based in colloidal dispersions of oxide nanocrystals. The nanoparticles were obtained by a hydrolisis method, using SnCl2 and SbCl3 in ethanolic solutions. The residual halides were removed by dyalisis, obtaining a limpid and transparent colloidal suspension. By this, the method offers the advantage of producing ultrathin films without organic contaminants. This route was employed to produce films with 5, 10, 14, and 18 mol% Sb doping, with thickness ranging from 40 to 70 nm. The physical characterization of the samples showed a uniform layer deposition, resulting in good packing density and high transmittance. A preliminar electrical study confirmed the low electrical resistivity even in the ultrathin films, in such level similar of reported data. The method described is similar in some aspects to layer-by-layer (LbL) techniques, allowing fine control of thickness and interesting properties for ultrathin films, however, with low cost when compared to similar routes.

Spin transport in polycrystalline Sb films

Spin transport in polycrystalline Sb films has been studied by using NiFe∕Sb∕NiFe lateral spin valve devices. A clear spin valve effect was detected in the magnetoresistance measurements, which were carried out using a conventional four-terminal geometry. The observation of a memory effect in these results indicates that the spin valve signal originates from spin injection and detection determined by the magnetization orientations of the two ferromagnetic electrodes in the NiFe∕Sb∕NiFe device. From our analysis of the spin valve signals, the authors estimate that the spin diffusion length in the Sb film is ∼2.3μm, with an injected spin polarization across the NiFe∕Sb interface of 0.8% at 20K.

GaSb/AlGaSb COMPOUND SEMICONDUCTORS GROWN BY MOCVD FOR OPTOELECTRONIC APPLICATIONS

Al x Ga 1-x Sb films in the regime 0 ≤ x ≤ 0.30 have been grown by metalorganic chemical vapor deposition on GaAs and GaSb substrates using TMAl , TMGa and TMSb precursors. We report the effects of growth conditions on the optical properties. Samples grown at temperatures of 540°C, 580°C and 600°C and a V/III ratio of 1 have been investigated. The Al x Ga 1-x Sb layers grown at 580°C and 600°C with a V/III ratio of 1 and Al content in the range of 0.5% to 25% were found to exhibit excellent optical quality with a very high optical transmission at energies below the bandgap. The principle photoluminescence features observed are attributed to bound exciton and donor-acceptor transitions with FWHM comparable to the best values reported elsewhere.

Large magneto‐optic Kerr effect on double thin Mn/Sb films

AbstractThe magneto‐optic effects are known phenomena on magnetic media; these effects could be used in magneto‐optics storages and switches. Recently; these effect are used in inducing the spintronic as well. In the present work we have considered the Kerr and Faraday effects on double evaporated Mn/Sb thin films. We evaporated a 100 nm Sb film on a cleaned glass substrate and then a 100 nm Mn film on top of the Sb layer. The prepared double film has been annealed in vacuum at about 150 °C for 5 hours. Then the magnet‐optic hysteresis loop of film has been plotted. From the hysteresis loop the optical rotation was calculated. The measurement shows an optical rotation up to one degree which is quit reasonable for this media. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Au–Cu/p–CdTe/n–CdO/glass-type solar cells

Abstract The heterostructure design proposed by us for the photovoltaic (PV) solar cell is: Au–Cu/p–CdTe:Sb/n–CdO:F/glass. The CdO:F films were grown by the sol–gel method, in conditions in order to get low resistivity ∼4.5×10 −4 Ω-cm and an optical transmission higher than 85%. The CdTe:Sb films were prepared by means of the RF sputtering technique, in conditions to get resistivity value around 10 6 Ω-cm, high crystalline quality and higher grain size. The Au–Cu contacts were thermally evaporated. For the study of PV-heterostructure a systematic variation of the preparation parameters were carried out. The parameters involved in the manufacture of the cell, in order to look for the highest efficiency were: (A) For the deposit of the p-CdTe:Sb films, a low argon pressure of 2.5 m Torr and high substrate temperature of 450 °C. The CdTe:Sb film thickness was varied in the interval 4.5–11 μm. (B) For the activation of the heterostructure: (i) The treatment temperature in vacuum, after the CdTe is deposited, was varied in the 350–550 °C range and (ii) the treatment temperature in Ar atmosphere, after the heterostructure is dipped in CdCl 2 solution, was studied in the 400–510 °C range. (C) Optimization of the Cu–Au contact with the adequate Cu-film thickness. The highest energy conversion efficiency ( η ) value was 5.48%. This work reports a systematic study of the parameters involved in the solar cell manufacture, for the search of a better value of η .

Characteristics of Ti 0.97Co 0.03O 2:Sb 0.01 dilute magnetic semiconducting thin films deposited at 500 °C by pulsed laser deposition

Epitaxial Ti 0.97Co 0.03O 2:Sb 0.01(TCO:Sb) films were deposited on R-Al 2O 3 (1 1 0 2) substrates at 500 °C in various deposition pressures by pulsed laser deposition. The solubility of cobalt within the films increases with decreasing deposition pressure at a deposition temperature of 500 °C. The TCO:Sb films deposited at 5×10 −6 Torr exhibit a p-type anomalous Hall effect having a hole concentration of 6.1×10 22/cm 3 at 300 K. On the other hand, films deposited at 4×10 −4 Torr exhibits an n-type anomalous Hall effect having an electron concentration of about 1.1×10 21/cm 3. p- or n-type DMS characteristics depends on the change of the structure of TCO:Sb films and the solubility of Co is possible by controlling the deposition pressure.

Electronic structure of Sb monolayers on the Mo(110) surface

AbstractWe compare theory and experimental (LEED and EELS) studies of the atomic and electronic structure of adsorbed Sb layers on Mo(110). At half a monolayer coverage, Sb atoms occupy the “long‐bridge” (hollow) sites forming the (1 × 2) film structure. At this coverage, a dramatic decrease of surface density of states in vicinity of Fermi level results in a quasi dielectric state of the surface. With increasing coverage, direct lateral interaction between Sb atoms becomes increasingly important and leads to push‐out of some Sb atoms in the (2 × 3/2) surface unit cell from the adsorption sites that are favorable at lower coverages. Substantial overlap of orbitals of neighboring adatoms results in metallic state of adsorbed Sb film, as suggested from significant increase of DOS at Fermi level. In EEL spectra, the nonmetal to metal transition reveals itself also by appearance of the –7.8 eV peak, which may be explained by the interband transition from Sb s band to unoccupied p states above EF. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Properties of p-Type ZnO Grown by Oxidation of Zn-Group-V Compounds

ABSTRACTZnO:N and ZnO:Sb layers were obtained by thermal oxidation of Zn compounds with group-V elements. The films are polycrystalline, with the acceptor concentration in the range 1020 cm-3, and the background concentration of H of 5×1019 cm-3. Transport measurements reveal the p-type conductivity with the hole concentrations exceeding 1017 cm-3. Rich photoluminescence spectra involve excitons bound to neutral acceptors and donor-to-acceptor transitions. p-ZnO:N and p-ZnO:Sb films show transparency of about 85 % in the visible wavelength range, making these materials very promising for transparent electronics.

High-mobility Sb-doped p-type ZnO by molecular-beam epitaxy

Reproducible Sb-doped p-type ZnO films were grown on n-Si (100) by electron-cyclotron-resonance-assisted molecular-beam epitaxy. The existence of Sb in ZnO:Sb films was confirmed by low-temperature photoluminescence measurements. An acceptor-bound exciton (A°X) emission was observed at 3.358 eV at 8 K. The acceptor energy level of the Sb dopant is estimated to be 0.2 eV above the valence band. Temperature-dependent Hall measurements were performed on Sb-doped ZnO films. At room temperature, one Sb-doped ZnO sample exhibited a low resistivity of 0.2Ωcm, high hole concentration of 1.7×1018cm−3 and high mobility of 20.0cm2∕Vs. This study suggests that Sb is an excellent dopant for reliable and reproducible p-type ZnO fabrication.

Growth and transport properties of Sb 2−xV xTe 3 thin films on sapphire substrates

Thin films of Sb 2− x V x Te 3 with x = 0 , 0.15, 0.32 and 0.35 have been grown on sapphire (0 0 0 1) substrates using molecular-beam epitaxy. With the increasing concentration of vanadium, the in-plane lattice constant of Sb 2− x V x Te 3 films decreases while the c-axis lattice constant shows a very small increase. The electrical resistivity of Sb 2− x V x Te 3 films decreases by an order of magnitude when V is substituted on the Sb sublattice. The Hall effect measurements show an increase in the concentration of holes as the content of vanadium increases.

Ferromagnetic and electrical properties in ferromagnetic semiconductor Ti1−xCoxO2−δ:Sb thin films grown by pulsed laser deposition

Rutile Ti1−xCoxO2−δ:Sb thin films were grown on R-Al2O3 substrates by pulsed laser deposition and investigated for the magnetic and electrical properties with deposition temperature. The Sb doping effect in rutile Ti1−xCoxO2−δ thin films was also investigated with deposition temperature. The Ti0.97Co0.03O2−δ:Sb films exhibited a ferromagnetic property and an anomalous Hall effect at room temperature. In Ti0.97Co0.03O2−δ:Sb films deposited at 700 °C, the segregation of Co and Sb elements occurred at near interface between the films and substrate. The Sb doping effect in Ti0.97Co0.03O2−δ films deposited at 500 °C increases the charge carrier density, film resistivity, and decreases the saturation magnetization. An anomalous Hall resistivity of the films increases from 0.1 to 0.14μΩcm at 8 kOe by codoping of Sb in Ti0.97Co0.03O2−δ films.

UV–violet photoluminescence emitted from SnO 2:Sb thin films at different temperature

Antimony-doped tin oxide (SnO 2:Sb) thin films were prepared on glass substrates by rf magnetron sputtering techniques. The obtained samples are polycrystalline films with rutile structure of pure SnO 2 and have preferred orientation of (110) direction. A strong photoluminescence (PL) band is observed at room temperature from the obtained SnO 2:Sb films. The PL spectrum consists of a strong UV–violet peak at 392 nm (about 3.16 eV), a shoulder near 430nm (about 2.88 eV) and a broad feeble peak near 520 nm (about 2.44 eV). The intensity of PL peak increases sharply with the enhancement of oxygen partial pressure and the decrease of measuring environmental temperature. The observed room temperature UV–violet emission is ascribed to the donor–acceptor band transition resulting from Sb doped effect.

Sb excimer-laser doping in ZnO films prepared by oxidation of sulfide on Si

ZnO thin films were formed by oxidation of ZnS films on Si substrates. Sb doping of ZnO films was tried by laser irradiation of ZnO deposited with Sb. Although p-type ZnO:Sb film was not obtained, it was observed that the laser irradiation increased the near-ultraviolet (NUV) emission intensity, whereas the visible emission of oxygen vacancies decreased. Moreover, the resistance of the laser-irradiated ZnO:Sb films was higher than that of films without irradiation. These results show that Sb compensates the oxygen vacancy; as a result, the electrons are neutralized by holes generated by the dopant (Sb).