Formation of Ultrathin Semiconductor Films by CdS Nanostructure Aggregation

Facci, Paolo; Erokhin, Victor; Тронин, А. А.; Nicolini, Claudio

doi:10.1021/j100101a036

Cited by 69 publications

(74 citation statements)

References 6 publications

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“…lc, consists of the formation of CdS nanoclusters inside the LB film by exposing precoated tips to an atmosphere of H2S for 20 min, a time period that turned out to be sufficient to get the reaction completed for such a film thickness (23).…”

Section: Methodsmentioning

confidence: 99%

Room-temperature single-electron junction.

Facci¹,

Erokhin²,

Carrara³

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

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The design, realization, and test performances of an electronic junction based on single-electron phenomena that works in the air at room temperature are hereby reported. The element consists of an electrochemically etched sharp tungsten stylus over whose tip a nanometer-size crystal was synthesized. Langmuir-Blodgett films of cadmium arachidate were transferred onto the stylus and exposed to a H2S atmosphere to yield CdS nanocrystals (30-50 A in diameter) imbedded into an organic matrix. The stylus, biased with respect to a flat electrode, was brought to the tunnel distance from the film and a constant gap value was maintained by a piezo-electric actuator driven by a feedback circuit fed by the tunneling current. With this set-up, it is possible to measure the behavior of the current flowing through the quantum dot when a bias voltage is applied. Voltage-current characteristics measured in the system displayed singleelectron trends such as a Coulomb blockade and Coulomb staircase and revealed capacitance values as small as 10-19 F.For several years, single-electron phenomena have attracted the interest of researchers from basic and applied viewpoints (1-5). These kinds of phenomena can take place when a small conductive particle is placed between two electrodes and is spaced asymmetrically from them by two tunneling gaps. In this case, a quantized charging of the particle resulting in the quantized increase of the current that flows through the system when a bias voltage is applied is observed. The conditions for achieving such a situation imply that the capacitance C of the structure is small enough to make the charging energy of the junction (e2/2C) exceed the thermal energy kT. Namely, roomtemperature monoelectron junctions typically require particles not larger than several nanometers in diameter (quantum dots) (6-9).The possibility of controlling the signal at the level of a single electron will allow the realization of a new class of devices (3)(4)(5)10). These new electronic junction can be foreseen to display very low energy consumption, an ultra-high scale of integration, and fast commutation time.The increasing interest in monoelectron phenomena has stimulated researchers to develop techniques for forming suitable junctions. The main efforts have focused upon the minimization of the element sizes by exploiting lithography processes. Striking results have been recently achieved in this field (11-13). As an alternative to this approach, techniques for nanoparticle formation, localization, and contacting with scanning tunneling microscope (STM) tip have been developed. Consequently, low (14-18) and room (6, 7) temperature monoelectron phenomena have been reported on nanoclusters of various natures and have been synthesized by different methods involving physical and chemical approaches. Among the different methods for producing these granules, one of the most promising seems to be that based on the synthesis of nanometer-size semiconducting granules from LangmuirBlodgett (LB) film precursors (7)....

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Section: Methodsmentioning

confidence: 99%

Room-temperature single-electron junction.

Facci¹,

Erokhin²,

Carrara³

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

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“…7,136,137 Using an amphiphilic polymer, poly(maleic acid)octadecanol, and a cadmium or lead salt, ordered LB structures can be prepared and, when treated with H 2 S, result in CdS and PbS nanoparticle layers in an ordered organic matrix. 130 A similar approach 155 has been used in the preparation of films consisting of CdS nanostructures on a substrate. The substrate was obtained by the selective removal of a fatty acid matrix from LB films of cadmium arachidate, which were then exposed to H 2 S. Scanning tunneling microscopy images showed 155 that the films consist of closely interconnected CdS particles.…”

Section: Processabilitymentioning

confidence: 99%

“…130 A similar approach 155 has been used in the preparation of films consisting of CdS nanostructures on a substrate. The substrate was obtained by the selective removal of a fatty acid matrix from LB films of cadmium arachidate, which were then exposed to H 2 S. Scanning tunneling microscopy images showed 155 that the films consist of closely interconnected CdS particles. With the resulting particle dimensions depended on the initial number of cadmium arachidate layers.…”

Section: Processabilitymentioning

confidence: 99%

Nanocrystalline Semiconductors: Synthesis, Properties, and Perspectives

2001

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The synthesis and study of so-called "nanoparticles", particles with diameters in the range of 1-20 nm, has become a major interdisciplinary area of research over the past 10 years. Semiconductor nanoparticles promise to play a major role in several new technologies. The intense interest in this area derives from their unique chemical and electronic properties, which gives rise to their potential use in the fields of nonlinear optics, luminescence, electronics, catalysis, solar energy conversion, and optoelectronics, as well as other areas. The small dimensions of these particles result in different physical properties from those observed in the corresponding macrocrystalline, "bulk", material. As particle sizes become smaller, the ratio of surface atoms to those in the interior increase, leading to the surface properties playing an important role in the properties of the material. Semiconductor nanoparticles also exhibit a change in their electronic properties relative to that of the bulk material; as the size of the solid becomes smaller, the band gap becomes larger. This allows chemists and material scientists the unique opportunity to change the electronic and chemical properties of a material simply by controlling its particle size. Research has already led to the fabrication of a number of devices. This review aims to highlight recent advances in the synthesis of compound semiconductor nanoparticle materials and their potential use in areas such as catalysis and electronic device fabrication.

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“…LB multilayers of divalent fatty acid salts like cadmium arachidate/ stearate have been most extensively used to develop and understand the growth process of semiconducting chalcogenide (e.g. CdS) nanoclusters [4][5][6][7][8][9][10]. However, inspite of the extensive work on the CdS-fatty acid system, the issue of size and shape of CdS nanoclusters still remains to be completely understood.…”

Section: Introductionmentioning

confidence: 99%

Structure of CdS–arachidic acid composite LB multilayers

Kumar

Narang

Major

et al. 2002

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Langmuir-Blodgett (LB) multilayers of cadmium arachidate were used as precursors to grow semiconducting CdS nanoclusters. The formation of CdS in the multilayers was determined by Fourier transform-infrared (FT-IR), ultraviolet-visible (UV-vis) and Raman spectroscopy. The structural changes occurring as a consequence of CdS formation have been characterized using X-ray reflection (XR) and grazing incidence X-ray diffraction (GIXD) techniques. The CdS containing composite multilayers exhibit the presence of two types of molecular domains, one with close packed herringbone arrangement and the other with tilted molecular chains with no in-plane order. The structural and spectroscopic evidences together suggest that the CdS nanoclusters formed within the arachidic acid LB matrix are quasi two-dimensional in nature with lateral dimension 5-10 nm and thickness 1.1 nm.

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Formation of Ultrathin Semiconductor Films by CdS Nanostructure Aggregation

Cited by 69 publications

References 6 publications

Room-temperature single-electron junction.

Room-temperature single-electron junction.

Nanocrystalline Semiconductors: Synthesis, Properties, and Perspectives

Structure of CdS–arachidic acid composite LB multilayers

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