Bi2S3 Thin Films Research Articles

Inclusion of polyaniline in electrodeposited bismuth sulphide thin films: Synthesis and characterization

Structural, electrical and optical properties of polyaniline (PAni) doped Bi2S3 composite thin films prepared by electrodeposition method are reported. X-ray diffraction pattern indicates its polycrystalline nature and crystallite size increases with increase in the concentration of PAni. FTIR studies reveal that the dopant PAni has affected the absorption phenomenon in the IR region of the Bi2S3 thin films. The optical band gap energy is found to be 1.91eV for as-deposited Bi2S3 thin film and it decreases with increase in the concentration of PAni. The morphology of the doped films changes due to the addition of PAni. Electrical studies indicate that the conductivity increases with increase in the concentration of PAni. The conduction results from a hopping due to localized states in the temperature range 300–358K. Above 358K, the conduction process is explained by the traps at grain boundaries of partially depleted grains.

Study of the optimal condition for electroplating of Bi2S3 thin films and their photoelectrochemical characteristics

Bismuth sulfide (Bi2S3) thin films were electrodeposited from non-aqueous dimethyl sulfoxide medium containing Bi(NO3)3 and thiourea as the precursor salts, triethanol amine as the complexing agent, and TritonX-100 as the surface active agent. The prepared films were subjected to rigorous experimentation in order to validate their potential candidature for solar cells. The films exhibited band gap energy of ∼1.3 eV and resistivity of the order of 2 × 106 Ω cm at room temperature as was obtained from UV–Vis spectroscopy and four-probe measurements, respectively. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy dispersive analysis of X-ray were employed to reveal the morphology, structure, and chemical composition of the film matrix. The Bi2S3 films were found to be non-decomposable up to the temperature of 1,000 °C with the help of thermogravimetry–differential thermal analysis. The Nyquist and Mott–Schottky plots derived from electrochemical impedance spectroscopy measurements provided important information regarding electrical and semiconducting properties of the films. The n-type film with a donor density of the order of ∼1023 m−3 displayed reasonable photoactivity under illumination and is recommended as a promising candidate for potential photoelectrochemical applications.

Electrochemical Deposition of Bi2S3 Thin Films Using Dimethylsulfoxide as a Solvent

thin films with different morphology and crystallite size were electrodeposited on conducting glass substrates from a dimethylsulfoxide solution of bismuth chloride and elemental sulfur at various temperatures. Porous films, constituted of open-packed nanoparticles , were obtained at low temperature . Dense films were obtained in the temperature range of . They were formed of larger close-packed nanocrystals arranged in columnar agglomerates. Electrodeposition at higher temperatures resulted in open-packed large nanocrystals that constitute a microstructured film. The stoichiometry of the films was confirmed by chemical analysis. However, X-ray diffraction indicated distortions in lattice. Deposition temperature was found to influence the distortion, with the smallest distortion observed for the highest temperature . Optical gaps in the range were estimated for the obtained films. The influence of the morphology and structural defects on the optical properties of films was also discussed.

Bismuth Sulfide Thin Films with Low Resistivity on Self-Assembled Monolayers

Using self-assembled monolayers (SAMs), highly crystalline bismuth sulfide thin films with low electrical resistivity have been prepared from aqueous solution at low temperature (40-70 degrees C). The nucleation and growth process of Bi2S3 thin films was investigated in detail by XPS, AES, SEM, XRD, SAED, and HRTEM. Solution conditions have marked effects on the microstructure, growth rate, and mechanism of Bi2S3 films. Increased solution temperature resulted in a higher growth rate and a shorter induction time due to a higher supersaturation degree. In the solution of pH 1.12, homogeneous nucleation and the attachment process dominated the formation of Bi2S3 films. In contrast, at pH 0.47 Bi2S3 thin films were formed via heterogeneous nucleation and growth. The c-axial orientation of bismuthinite films was enhanced with the increase of reaction time. By controlling the solution supersaturation and reaction duration, highly crystalline Bi2S3 films composed of closely packed and coalescent crystallites could be realized, whose dark electrical resistivity could reach as low as 0.014 Omega cm without any post-treatment.

Optical and electrical properties of Bi2S3 films deposited by spray pyrolysis

Thin films of Bi2S3 were prepared by spray pyrolysis method. Optical constants, electrical and photoelectrical studies have been carried out on these films. The optical constants confirm that the Bi2S3 thin film has a direct band gap of 1.69 eV. The Hall Effect measurements indicate that the Bi2S3 thin films prepared by spray pyrolysis method are n-type in nature with a carrier concentration of 3.51×1017 cm−3. An activated process with activation energy of 65 meV governs the conduction in these films. The photoconductivity measurement indicates the presence of continuously distributed localized gap states in this material.

Structural characterization of chemically deposited Bi2S3 and Bi2Se3 thin films

Simple and inexpensive chemical deposition methods were used to deposit bismuth trisulfide (Bi2S3) and bismuth triselenide (Bi2Se3) thin films onto amorphous glass substrate at relatively low temperatures. Deposition parameters are optimized to get nanocrystalline films. These films are used for structural, surface morphological and compositional analyses. Stoichiometry and film formation are confirmed by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDAX) and Rutherford back scattering (RBS) analyses. Surface coverage and roughness of the films are studied from scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. High resolution transmission electron microscopy (HRTEM) study has confirmed the nanostructure of Bi2S3 and Bi2Se3 films.

Solid-State Reactions in CdS–Bi2S3 Thin Films

Structural, electrical, and optical data are used to elucidate the mechanisms of solid-state reactions in thin CdS–Bi2S3 films prepared by spray pyrolysis. The results indicate the formation of substitutional solid solutions and a chemical compound and intercalation of Cd between layers of Bi2S3 .

Comparison of the Properties of Bismuth Sulfide Thin Films Prepared by Thermal Evaporation and Chemical Bath Deposition

Highly oriented polycrystalline Bi2S3thin films with crystallinities superior to those obtained in chemically deposited Bi2S3thin films were prepared by direct evaporation of bismuth sulfide precipitate. The XRD patterns of these films show preferential growth of bismuth and bismuthinite planes, and this growth could be correlated to substrate temperature and substrate type. For films deposited on glass substrates at room temperature, the XRD pattern shows an incipient growth of Bi2S3(bismuthinite) along the [020], [220], and [021] directions. At these angles, Bi planes also diffract and might be the major component of this alloy. XRD spectra of films deposited on bare glass in the substrate temperature range 150–300°C show that the film growth evolves from an oriented to a more random pattern. At a substrate temperature of 250°C, the crystallization of bismuth and bismuthinite is accelerated on glass substrates with a Cr coating and inhibited on glass substrates with a SnO2coating. The reflectance spectra of the films deposited at 250°C on uncoated and SnO2-coated glass substrates show that the crystallinity is dominated by Bi2S3, whereas in films deposited on a Cr grid Bi is a strong component. The optoelectronic properties of the deposited films indicate very conductive layered structures withEgvalues in the range 1.2–1.6 eV. Compared with the above, chemically deposited thin films were less crystalline and more stoichiometric, with a lower conductivity and higher optical band gap (1.5–2.0 eV). The possible application of these films in heterojunction and photoelectrochemical devices is suggested.

Structural and optical properties of electrodeposited Bi2S3, Sb2S3 and As2S3 thin films

Thin films of Bi2S3, Sb2S3 and As2S3 have been prepared by the electrodeposition technique from aqueous acidic baths using Na2S22O3 as a sulphide source. The films deposited from an EDTA-complexed bath are thin, uniform and adherent to the substrate. The electrodeposition potentials were estimated by polarization curves. The structural and optical properties of the films have been studied. The X-ray diffraction pattern of the films shows that they are polycrystalline. The estimated optical bandgap energies for Bi2S3, Sb2S3 and As2S3 are 1.58 eV, 1.74 eV and 2.35 eV respectively.

Chemically deposited ZnS thin films: application as substrate for chemically deposited Bi2S3, CuxS and PbS thin films

Chemical deposition of good quality ZnS thin films from aqueous solutions containing zinc sulphate, NH3/NH4Cl buffer (pH 10), triethanolamine and thioacetamide is described. It is shown that the presence of these films on glass substrates offers various advantages in the case of chemically deposited metal sulphide thin films: (i) improved adhesion of Bi2S3 thin films, which is vital for growing films of thickness >0.2 mu m for semiconductor applications and in metal sulphide thin film (MSTF) photography based on photoaccelerated chemical deposition; (ii) improved adhesion of CuxS films, offering the choice of different shades of colours for the same integrated transmittance in the visible region of approximately 20% in solar control coatings and the possibility of multiple-dip deposition of CuxS films to enhance the film thickness, enabling the realization of solar absorptance of approximately 90%; and (iii) reduced reflectance in the visible light which can reduce the glare from PbS solar control coatings and improve the solar absorptance in thicker PbS coatings and offer better contrast in MSTF photography.

Amorphous-crystalline transformation and conductivity enhancement in annealed bismuth sulphide thin films

Post-deposition vacuum annealing of chemically deposited Bi2S3 thin films has been found to enhance the dark conductivity of the films from approximately=10-7 Omega cm-1 to approximately=102 Omega -1 cm-1 and the photoconductivity from approximately 10-5 Omega cm-1 to approximately=102 Omega cm-1. Such increase is attributed to (i) an amorphous-to-crystalline transformation of the setting in at approximately=175 degrees C, confirmed by X-ray diffraction studies and (ii) loss of sulphur from the film during vacuum annealing at temperatures >200 degrees C, confirmed by the absence of this effect in air/nitrogen annealing. In the case of annealing in air, the competing effect of mobility enhancement by amorphous-crystalline transformation and mobility depreciation by oxygen chemisorption at the intergrain region is seen to contribute to a dark conductivity and photoconductivity maxima at an annealing temperature of approximately=200 degrees C.

ChemInform Abstract: Chemical Methods for the Deposition of Thin Films of Bi2S3.

AbstractUniform Bi2S3 thin films can be deposited on glass substrates from aqueous solutions containing BiCl3, Na2S2O3, and EDTA at pH 2‐3 (HCl) or at pH 10‐11 (NaOH).

Characterization of as-grown and iodinated Bi2S3 thin films on silicon and quartz substrates by XRD

Bi2S3 thin films are grown on 〈100〉 silicon and 〈001〉 quartz substrates. The as-grown samples are found to be polycrystalline and cryptocrystalline on silicon and quartz, respectively. When iodised in iodine vapour for different hours, BiI3 is formed in the films with the c-axis oriented perpendicular to the substrate. X-ray diffraction studies are carried out to characterize the films. Auf〈100〉-Silizium-und 〈001〉-Quarzsubstrate werden dunne Bi2S3-Schichten aufgebracht. Die nach dem Aufbringen unbehandelten Proben sind polykristallin auf Silizium und kryptokristallin auf Quarz. In im Joddampf uber verschiedene Stunden behandelten Schichten wird BiJ3 gebildet mit einer zum Substrat senkrecht orientierten c-Achse. Zur Charakterisierung der Schichten werden Untersuchungen der Rontgenstrahlbeugung durchgefuhrt.

ChemInform Abstract: A Chemical Method for the Deposition of Bismuth Sulfide Thin Films.

AbstractAroom temp. Chemical method for the deposition of Bi2S3 thin films on a glass substrate has been developed based on the reaction between the triethanolamine complex of Bi" and thioacetamide in basic media.

Electrical properties of Bi2S3 thin films prepared by the dip-dry method

Bi2S3 thin films have been prepared by the dip-dry method and their electrical properties such as conductivity, thermoelectric power and spectral response of photoconductivity were investigated. Some uncommon findings, such as a simultaneous increase in conductivity and thermoelectric power with thickness of film, are explained by Seto's model for polycrystalline silicon film duly modified for in homogeneities.