Sb Deposition Research Articles

Influence of the growth parameters of p-CdTe thin films on the performance of Au–Cu/p-CdTe/n-CdO type solar cells

R.F. sputter deposition of Sb doped CdTe thin films was carried out with targets containing different amounts of antimony ( C T: 0, 2.5, 10 and 20 at.%). The substrates were kept at different temperatures ( T s) of 200, 275, 350 and 450 °C. Three different argon pressure values: 2.5, 5 and 15 mTorr were used. The lowest dark resistivity ( ρ) at room temperature (RT) was 9.0 × 10 5 Ω cm, which is one of the lowest values reported in the literature for Sb doped CdTe. Highly transparent (∼90%) and conductive ( ρ = 3.7 × 10 −4 Ω cm) F doped CdO (n-type) thin films, prepared at room temperature by the sol–gel method, were employed as window and top-contact. The configuration of the fabricated solar cell was (Au–Cu)/p-CdTe/n-CdO/glass. Open-circuit voltage ( V oc) and short-circuit current density ( J sc) at room temperature have the highest values for high T s, low P g and C T = 10 at.%. Despite the fact that V oc and J sc are lower than those reported in the literature, we think this work is useful as a basis for the search of more competitive CdTe/CdO based PV devices.

Lithogenic, oceanic and anthropogenic sources of atmospheric Sb to a maritime blanket bog, Myrarnar, Faroe Islands

Antimony concentrations were measured in a core collected from Myrarnar, a blanket bog on the Faroe Islands which has been accumulating peat for more than six thousand years. The vertical distribution of Sb indicates that it has been supplied to the peat exclusively from the atmosphere. Despite the proximity to the ocean, the contribution of Sb to the peat from marine aerosols amounts to less than ca. 10% of the natural inputs. Although the peat core contains four notable layers of volcanic ash originating from Iceland, these have not contributed significantly to the Sb inventory. However, the distribution of Sb closely resembles that of Pb, with most of the Sb found in peats dating from the industrial period. Peat samples dating from the Roman Period are not only contaminated with Pb, but also with Sb. Lead is known to be immobile in peat bogs, and in Europe has been derived predominantly from industrial sources for thousands of years. The correlation between Sb and Pb in the peat core from the Faroe Islands supports the hypothesis that Sb is also effectively immobile in peat, and that ombrotrophic bogs are faithful archives of atmospheric Sb deposition. The data presented here also reinforces the view that natural Sb inputs during the past two centuries are dwarfed by industrial inputs, and that human activities have affected the atmospheric Sb cycle to a comparable extent to that of Pb. The natural rate of atmospheric Sb deposition recorded by the peat core (0.33 microg m(-2) year(-1)) is remarkably similar to the value obtained from a Swiss peat bog (Etang de la Gruère) in the samples dating from ca. 6000 to 9000 years ago (0.35 microg m(-2) year(-1)) which suggests that the background rates obtained from the peat cores have broader validity. Consistent with previous work, the data from the Faroe Islands suggests that the natural flux of Sb to the global atmosphere may have been overestimated by a factor of ten, and that the influence of human activities has been underestimated to the same extent.

Increasing atmospheric antimony contamination in the northern hemisphere: snow and ice evidence from Devon Island, Arctic Canada

Adopting recently developed clean laboratory techniques, antimony (Sb) and scandium (Sc) deposition were measured in a 63.72 m-long ice core (1842-1996) and a 5 m deep snow pit (1994-2004) collected on Devon Island, Canadian High Arctic. Antimony concentrations ranged from 0.07 to 108 pg g(-1) with a median of 0.98 pg g(-1)(N= 510). Scandium, used as a conservative reference element, revealed that dust inputs were effectively constant during the last 160 years. The atmospheric Sb signal preserved in the ice core reflects contamination from industrialisation, the economic boom which followed WWII, as well as the comparatively recent introduction of flue gas filter technologies and emission reduction efforts. Natural contributions to the total Sb inventory are negligible, meaning that anthropogenic emissions have dominated atmospheric Sb deposition throughout the entire period. The seasonal resolution of the snow pit showed that aerosols deposited during the Arctic winter, when air masses are derived mainly from Eurasia, show the greatest Sb concentrations. Deposition during summer, when air masses come mainly from North America, is still enriched in Sb, but less so. Snow and ice provide unambiguous evidence that enrichments of Sb in Arctic air have increased 50% during the past three decades, with two-thirds being deposited during winter. Most Sb is produced in Asia, primarily from Sb sulfides such as stibnite (Sb2S3), but also as a by-product of lead and copper smelting. In addition there is a growing worldwide use of Sb in automobile brake pads, plastics and flame retardants. In contrast to Pb which has gone into decline during the same interval because of the gradual elimination of gasoline lead additives, the enrichments of Sb have been increasing and today clearly exceed those of Pb. Given that the toxicity of Sb is comparable to that of Pb, Sb has now replaced Pb in the rank of potentially toxic trace metals in the Arctic atmosphere.

Hypogene and supergene alteration of the Late Palaeozoic Ratburi Limestone during the Mesozoic and Cenozoic (Thailand, Surat Thani Province). Implications for the concentration of mineral commodities and hydrocarbons

An interdisciplinary study of the Upper Carboniferous to Middle Permian Ratburi Group, Peninsular Thailand, is presented. The investigation involved sedimentary petrography, inorganic geochemistry, Sr, C, O isotope analyses, micropalaeontology as well as radio-carbon age dating. Emphasis was placed on the post-depositional evolution of the Ratburi Limestone in the Surat Thani Province. The Holocene chemical residues and the various calcite and dolomite minerals which have formed since the Late Palaeozoic in the Ratburi Limestone are the product of a complex, multistage alteration which is called supergene and hypogene karstifications, respectively. Sedimentation took place in a shelf environment with some reefs evolving during the late Murgabian at the shelf margin. There was no pre-concentration of elements, except for Ca and F during sedimentation. Diagenetic neomorphism and cementation under marine and freshwater conditions caused the Ratburi Limestone to convert into a marble-like rock. Fabric-selective dolomitization is of local scale and has impacted only on part of the Ratburi Limestone during the Lower to Upper Permian. A significant enhancement of pore space and better conduits were generated during the Late Cretaceous epithermal alteration. The most favorable conditions for the accumulation of metals were provided during the high-temperature stage of epithermal alteration when a low-metal concentration with As, Zn, Sb, U, Co and Pb existed. Unlike the other elements, Sb was subject to a multiphase concentration, giving rise to a considerable Sb deposit in the region. The most recent stage of karstification produced numerous caves, dripstones, tufa terraces and encrustations around brine pools in the study area. This alteration originated from per descensum and per ascensum processes which may be traced back to 15,000 years before present. The alteration of the Ratburi Limestone may be subdivided into two parts. The prograde post-depositional alteration, beginning with diagenesis, reached its temperature climax during epithermal subsurface alteration I. The retrograde branch of alteration lasted until the most recent times. The initial stages deposition and diagenesis took place under more or less closed-system conditions relative to the succeeding stages of the prograde alteration which saw the strongest influx of metal-bearing brine during the epithermal stage I. The retrograde branch of alteration is “element-conservative”.

Structural study of the Ag(1 1 0) c(2 × 2)–Sb phase by low energy electron diffraction

This work concerns the deposition of Sb on the (1 1 0) clean surface of silver. Two structured phases have been observed: an Ag(1 1 0)(4 × 1)–Sb, with a Sb coverage of about 1.0 ML and an Ag(1 1 0) c(2 × 2)–Sb, with half the coverage of the first one. The structural determination of the Ag(1 1 0) c(2 × 2)–Sb phase has been performed by a standard LEED analysis and the results obtained indicate the presence of substitutional Sb atoms in the first atomic layer. The presence of the Sb substitutional atoms promotes an expansion in the first interlayer distance without any change in the surface thermal vibrational behaviour. Based on results obtained by this study and previously published ones, the substitutional site seems to be most energetically favourable for Sb atoms, in any of the low index surfaces of silver.

Electrodeposition of Sb on Au(1 0 0) at underpotentials: structural transition involving expansion of the substrate surface

We report an in situ scanning tunneling microscopic (STM) study of a structural transition of antimony on Au(1 0 0). Sb electrodeposition on Au(1 0 0) at underpotentials involves two successive stages: the reduction of irreversibly adsorbed Sb(III) and underpotential deposition of Sb. In the reduction stage, the Sb adlayer appears disordered on the surface. A remarkable structural transition takes place when potential is brought to initiate the underpotential deposition. An ordered structure of 2 −2 1 2 is observed accompanied by releasing of Au islands. Reversing of potential recovers the disordered state of the adlayer in a few minutes. Both the coverage and potential-dependent of Sb–Au interaction are responsible for the structural transition. A Sb-chemisorbed type of surface compound with a stoichiometric form of AuSb 2 is suggested. Together with the expansion of the Au(1 0 0) surface layer, this type of structural transition is unusual in the metal underpotential deposition.

Integrated rotating-compensator polarimeter for real-time measurements and analysis of organometallic chemical vapor deposition

We describe a single-beam rotating-compensator rotating-sample spectroscopic polarimeter (RCSSP) integrated with an organometallic chemical vapor deposition (OMCVD) reactor for in-situ diagnostics and control of epitaxial growth, and report representative results. The rotating compensator generates Fourier coefficients that provide information about layer thicknesses and compositions, while sample rotation provides information about optical anisotropy and therefore surface chemistry. We illustrate capabilities with various examples, including the simultaneous determination of 〈 ε〉 and α 10 during exposure of (001)GaAs to TMG, the heteroepitaxial growth of GaP on GaAs, and the growth of (001)GaSb with TMG and TMSb. Using a recently developed approach for quantitatively determining thickness and dielectric function of depositing layers, we find the presence of metallic Ga on TMG-exposed (001)GaAs. The (001)GaSb data show that Sb deposition is self-limiting, in contrast to expectations.

Ge dots self-assembling: Surfactant mediated growth of Ge on SiGe (118) stress-induced kinetic instabilities

The ordering of islands on naturally or artificially nanostructured surfaces is one of the most recent objectives among actual nanotechnology challenges. We show in this letter that, by a combination of two approaches, i.e., a two-step molecular beam epitaxy (MBE) deposition process and surfactant-mediated growth, we are able to obtain chains of nicely ordered ultrasmall islands of lateral size below 50 nm. The two-step MBE process consists of vicinal Si(001) surface self-patterning by SiGe growth instability and Ge dot ordering by subsequent Ge deposition on a SiGe template layer. The surfactant-mediated growth consists of submonolayer Sb deposition prior to Ge growth, in order to reduce the island size up to 25 nm. The best ordering of Ge islands is obtained when the island size matches the wavelength of the template layer.

The Xikuangshan Sb deposit hosted by the Upper Devonian black shale series, Hunan, China

The Xikuangshan Sb deposit hosted by the Upper Devonian black shale series, Hunan, China

Light Hydrocarbons in Fluid Inclusions and Their Constraints on Ore Genesis: A Case Study of the Songxi Ag (Sb) Deposit, Eastern Guangdong, China

Abstract The Songxi deposit is a newly discovered large Ag (Sb) deposit. By using a suite of high‐vacuum quadrupole gas mass spectrometer systems, the authors have recognized many kinds of light hydrocarbons in fluid inclusions of minerals. These hydrocarbons are mainly composed of C1‐C4 saturated alkanes, while the contents of C2‐C4 unsaturated alkenes and aromatic hydrocarbons are quite low, suggesting that the metallogenic processes have not been affected by magmatic activities. Chemical equilibrium studies show that these hydrocarbons may be a mixture of organic gases generated by microorganism activity and those by thermal cracking of type‐II kerogens (kukersite) in sedimentary host rocks, and the former may constitute more than two‐thirds, implying that microorganism might have played an important role in the metallogenesis. The equilibrium temperature of the latter is about 300°C, which is much higher than the geothermal temperature at the estimated depth of metallogenesis. Thus, the light hydrocarbons generated by thermal cracking of kerogens probably originated in the deep part of the sedimentary basins and then migrated through a long distance to shallower horizons of the basin. Based on the composition of light hydrocarbons in fluid inclusions, the authors infer that the Songxi deposit was formed in a continental rift. The analytical data presented in this paper support from one aspect the genetic model that the Songxi deposit may be a sedimentary hot brine transformed deposit instead of a submarine basic volcanic exhalation and low‐medium temperature volcanic hydrothermal fluid filling deposit proposed by most previous researchers.

Study of Sb adsorption on the Si(0 0 1)–In(4 × 3) surface

The process of Sb adsorption onto Si(0 0 1)–In(4×3) surface phase has been studied using scanning tunneling microscopy (STM), reflection high-energy electron diffraction (RHEED) and Auger electron spectroscopy (AES) techniques. Above 400 °C, Sb tends to destroy the initial In-induced phase and terminate the surface forming Sb/Si(0 0 1) interface. Between 400 and about 200 °C, however, the decomposition of In-induced reconstruction becomes partial; removing of In atoms from InSi bonds results in the relaxation of substrate atoms to the sequence of dimer rows separated by 4 a 0 which is also destroyed by further Sb adsorption. Below 200 °C, the (4×1) structure remains intact against Sb deposition. In this case, In and Sb atoms form disordered layer mediated by the corrugation of (4×1) structure.

Atomic structure and formation process of the Si(1 1 1)–Sb(√7 × √7) surface phase

During the study of Sb condensation on the Si(111)–In(√3×√3) surface phase we observed the formation of a new Sb-induced surface structure with (√7×√7) lattice below 450°C. This phase may not be prepared by direct Sb deposition on the Si(111) surface. Instead, the substitution for In atoms from T4 bonding sites by incoming Sb and formation of a γ-phase strongly determine the Sb(√7×√7) formation process. When the concentration of Sb exceeds the value of 0.2ML the irreversible γ√3→√7 phase transition occurs. Based on STM observations, the structural model for this reconstruction has been proposed.

Metal Adlayer-Induced Relaxation of Au(111) Reconstruction under Electrochemical Control

Underpotential deposition of Sb has been observed to induce a relaxation of Au(111) (√3 × 22) reconstruction to corrugation lines of trigonal networks. The triangles typically appear pairwise with an average length of the baselines of ∼20.2 ± 1.0 nm and a height of the triangles of ∼10.6 ± 1.4 nm at a corrugation height of ∼0.05 nm. The baselines of the trigonal network rotate by 30° with respect to the corresponding double rows of the (√3 × 22) reconstruction and align along one of the three {110} directions. An atomic resolution image reveals an apparent (√3 × √3) structure in the regions with hcp stacking sites enclosed by the triangles, which is attributed to the atomically dispersed surface alloy structure of Sb with the topmost Au atoms. Similar relaxation structures are observed with decreasing coverage via irreversible adsorption, although the size of the relaxation is alleviated. The surface alloying is confirmed by the creation of holes upon anodic stripping, the holes being confined at the conn...

Reversible Structure Transformation of Antimony Oxides on SiO2Relevant to Selective Catalytic Oxidation of Ethanol

Sb/SiO2 catalysts were prepared by chemical vapor deposition of Sb(OEt)3 on a SiO2 surface followed by water vapor admission and calcination. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectra, and X-ray absorption fine structure and by catalytic performance for selective oxidation of ethanol. At low loadings (2−4 wt %) Sb(OEt)3 reacted with surface OH groups on the SiO2 surface to form surface-attached Sb(III) species. At high Sb loadings (>5 wt %), in addition to the attached Sb(III) species, crystalline Sb2O3 species were formed after exposure to water vapor. The amount of crystalline Sb2O3 species increased with Sb loading, and 30−50% of Sb species existed as crystalline Sb2O3 at 7−12 wt %. Most of the Sb(III) species remained trivalent after calcination. On the other hand, the crystalline Sb2O3 was oxidized to Sb(V) and spread on the SiO2 surface. The spread antimony oxide species were active for selective catalytic oxidation of ethanol through a redox mechanism. When ...

A new model for Sb deposition in the French Massif Central based upon thermodynamic modeling of the mineralizing fluid

A new model for antimony (Sb) deposits in the Haut-Allier area of the French Massif Central is proposed, based on thermodynamic modeling of the mineralizing fluid. The Sb deposits in the research area contain stibnite and berthierite as Sb minerals, and occur in veins crosscutting gneiss lenses. The surrounding schist host rock is non-mineralized. Thermodynamic modeling of the ore-fluid shows that no Sb minerals will precipitate if the fluid is buffered by alteration reactions in the host rock. However, brittle fractures, developed in the gneiss lenses during uplift, channelize the fluid flow, which eventually results in the loss of contact with the buffering environment. With lowering temperatures the Sb solubility sharply decreases in this unbuffered fluid and Sb-minerals precipitate. The schists continue to allow pervasive fluid flow instead, buffering the fluid outside the stibnite stability field and no Sb deposits are therefore present.

Vibrational properties of the Sb:InP( [formula omitted]) surface

We have studied the lattice dynamics of a monolayer antimony-covered InP(1 1 0) surface by combining the density-functional-pseudopotential theory and an adiabatic bond-charge model. It is found that the deposition of Sb on InP(1 1 0) leads to several characteristic vibrational features. In particular, due to the large mass of the Sb atom, the Rayleigh vibrational mode becomes fully localised near the zone edges, lying well below the acoustic continuum of bulk InP. While the surface vibrational modes are removed from the interior of the acoustic-optical gap region, there are still reasonably large peaks in the density of states in the gap towards the bulk continuum edges.

Twinned InSb molecular layer on Si([formula omitted]) substrate

We studied the formation of a twinned InSb molecular layer on Si(111) substrate (epitaxial relation InSb[112]∥Si[110]) by depositing 1-ML Sb on Si(111)–In(4×1) reconstruction at 210°C, using reflection high-energy electron diffraction, X-ray photoelectron spectroscopy and Auger electron spectroscopy. Sb adsorption replaces Si–In bonds in the In(4×1) reconstruction and forms Si–Sb bonds. Codeposition of In and Sb on the Si(111)-7×7 surface results in the formation of an InSb film with no twin (epitaxial relation InSb[110]∥Si[110]). Annealing this twinned InSb layer above 350°C resulted in the formation of Si(111)–Sb(3×3) structure, and the coalescence of most of the In. However, direct Sb deposition on Si(111)-7×7 at 350°C results in only disordered phase. Softening of the Si/Sb interface by the Si–In and In–Sb reactions is proposed to be responsible for the formation of the InSb twinned layer (at 210°C) and 3×3 structure by Sb (at 350°C).

Epitaxial growth of Sb thin film and chemical reaction of Sb-induced surface reconstruction on Si(1 1 3)3×2

Antimony layers deposited on a Si(1 1 3)3×2 surface are investigated with low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). No long-range order is obtained in the room temperature grown Sb layer. Post-growth annealing at about 100°C restores long-range order and produces two-domain sixfold symmetric hexagonal structure. The tilted angle between two domains is 33.6°, which corresponds to the angle between [ 7 ̄ 4 1] and [4 7 ̄ 1] direction on bulk-terminated Si(1 1 3) plane. Sb (MNN) and Si (LMM) AES peak-to-peak intensities as a function of Sb deposition time at 100°C indicate that the overlayer structure grows a layer-by-layer fashion on the Si(1 1 3) surface at least up to two full molecule layer. Simple overlayer structure model, which consists of Sb n ( n=1–4) molecules, is suggested. Depending on the substrate temperatures above 300°C and Sb coverages, the 1×1, 2×2, and 2×5 reconstructions are formed successively. Oxygen exposure shows quite different surface chemical reactivities depending on the surface structures. The 1×1 and 2×2 surfaces are strongly passivated, on the other hand, the 2×5 surface reacts with oxygen relatively well. The different chemical reactivity is explained by the existence of the Sb lone pairs and Si dangling bonds in the unit cells.

Metallogeny, Minerogenic Series, and Gold Mineralization of the Qinling Orogen, China

The Qinling orogen extends 1650 km E-W and has a width of 95-255 km. It has a long evolutionary history of ∼3.02 Ga and a mineralization history of approximately 2.5 Ga. There are more than 400 mineral deposits of Au, Ag, Pb, Zn, Sb, Hg, Mo, W, Fe, Ni, Mn, rare elements, REE, U, V, P, As, Ba, Sr, Ti, Al, pyrite, gypsum, trona, halite, glauberite, mirabilite, blue asbestos, fluorite, rock crystal, mica, vermiculite, graphite, kyanite, andalusite, talc, fireclay, and K-feldspar in the Qinling orogen and adjacent areas. The deposits were formed in six tectono-minerogenic cycles and have been grouped into 21 regional minerogenic series. The metallogeny of the Qinling orogen is closely associated with the tectonic evolution of the orogen, and most of the ore deposits were formed in two important metallogenic periods: (1) Middle Proterozoic to Early Paleozoic, which was characterized by spreading and rifting-related minerogenetic processes; during this period, the minerogenic series are directly associated with basic-ultrabasic magmatism and marine volcanism resulting from spreading-rifting and deep faulting; (2) Mesozoic, when mineralization was controlled by intracontinental subduction and postorogenic relaxational taphrogenesis or extension; the minerogenetic series are associated with intermediate-acid magmatism and terrestrial volcanism. Gold is one of the most important ore-forming commodities in the Qinling orogen. Over 80% of those gold deposits were formed in the Mesozoic and Cenozoic and are related genetically to magmatism, terrestrial volcanism, and alluvial sedimentation. Most gold deposits in the Qinling orogenic belt are of hydrothermal origin. The Dashui-type gold deposits may be a new category of high-sulfi-dation epithermal gold deposits hosted by carbonate rocks of the Upper Paleozoic and Triassic in the southwestern part of the Qinling orogen. Shuangwangtype gold deposits in the middle of the Qinling orogen are characterized by low-grade (but large in terms of tonnage) ores hosted by brecciated and banded albitites, which are thought to have been formed by Yanshanian (late Mesozoic) magmatic-hydrothermal fluids injected into the Devonian sedimentary rocks. Carlin-type, quartz vein-type, and placer-type deposits also are important in this continental orogenic belt and adjacent areas.

Sb adsorption on Si(1 1 1)–In(4 × 1) surface phase

We studied the formation of first InSb molecular layer on the Si(111) substrate by depositing about 1ml of Sb on In(4×1) reconstruction in the temperature range 170–350°C, using reflection high-energy electron diffraction (RHEED) and auger electron spectroscopy (AES). The element Sb deposition at 210°C resulted in the formation of an epitaxial InSb molecular layer (not psudomorphic). This surface showed a weak 1×1 RHEED pattern with a ‘dramatic rotation’ of the surface layer with respect to the Si substrate. At this temperature, the deposited Sb atoms do not replace the Si–In bonds. However, Sb deposition above 250°C resulted in the replacement of In-layer by Sb atoms. Subsequently Sb formed various well-ordered reconstructions, which are highly sensitive to the deposition conditions. 1ml Sb deposition on In(4×1) reconstruction at 260, 300 and 350°C formed 2×1, 2×2 and √3×√3 structures, respectively. All these surface phases produced very sharp RHEED patterns indicating the long-range order. For Sb depositions above 300°C, AES results showed negligible In presence on the Si surface, suggesting the coalescence of In reconstruction by the adsorbed Sb. This replacement reaction drastically changes the bonding nature of the Si surface, which explains the role played by the In(4×1) reconstruction for the InSb growth on Si(111) substrate.