In2S3 Thin Films Research Articles

Optoelectronic properties of undoped and Al, B and Ga-doped In2S3 thin films grown by CBD on flexible PET/ITO substrates

Undoped and Al, B and Ga-doped In2S3 thin films were deposited on flexible PET/ITO substrates using chemical bath deposition by varying the deposition temperatures (60, 70, 80 and 90 °C) and growth times (120, 150 and 180 min). Citric acid was used as complexing agent along with indium trichloride and thioacetamide as indium and sulfur sources, respectively. The structural, optical and electrical properties of In2S3 thin films were analyzed by Raman spectroscopy, UV-Vis transmittance spectroscopy and Hall Effect measurement. Structural analysis indicated the tetragonal phase of In2S3 films. The optical characterization showed a maximum transmittance of 80% in the visible region. The band gap energy of In2S3 thin films was tuned from 2.06 to 2.94 eV with respect to doping elements and experimental parameters. The electrical characterization showed n-type conductivity for both undoped and doped In2S3 thin films along with the resistivity values between 1 × 10−2 and 1 × 105 Ωcm.

Morphological and nonlinear optical properties of Al:InSe thin films

Herein, an Al:InSe thin film is designed and synthesized by the direct current-radio frequency sputtering method. The obtained Al:InSe films possess smooth surface morphology with Al:InSe particles dispersion on sapphire substrates. Via aluminum (Al) doping, two-photon absorption and the doping energy level together induced free-carrier absorption, established on the conduction band. Al:InSe thin film displays a broad-band nonlinear absorptive band arising from 532 nm to 1064 nm, and exhibits effective third-order (βeff) and fifth-order nonlinear absorption coefficients (γeff) and relaxation time (τ) under femtosecond pulsed laser. This study provides a potential method for preparing Al:InSe thin film to investigate their nonlinear optical properties.

Optical and Photoelectric Properties of GaS Thin Films and GaS/InSe Heterostructure

GaS thin films have been grown by the SILAR method, their structures have been analyzed, and their optical and photoelectric properties have been investigated. The internal structure of the samples obtained have been studied using X-ray diffraction (XRD) analysis, atomic force microscopy (AFM), energy-dispersive X-ray (EDX) spectroscopy, and scanning electron microscopy (SEM). The GaS band gap has been determined from the absorption spectrum. p-GaS/n-InSe heterojunctions have been formed on the basis of GaS crystals and InSe thin films. Current–voltage, optical, photoelectric, and luminescence characteristics of p-GaS/n-InSe heterojunctions have been experimentally investigated.

Optoelectronic properties of In2S3 thin films measured using surface photovoltage spectroscopy

In recent years, In2S3 thin films were widely used as buffer/window layer in thin film solar cells as an alternative to toxic CdS. In the present work, we demonstrate the potential of surface photovoltage spectroscopy for estimation of minority carrier diffusion length, band gap energy and refractive index of thermally evaporated In2S3 thin films. The estimated minority carrier diffusion length of In2S3 thin films from SPV measurements were 0.112 μm and 0.052 μm for films annealed at 250 and 300 °C respectively.

Computational study and characteristics of In2S3 thin films: effects of substrate nature and deposition temperature

In this work, we investigate the effects of both growth temperature and substrate nature on different properties of indium sulfide thin films prepared by chemical vapor deposition method using triphenylphosphine sulfide as a sulfur precursor. The structural, morphological, and optical properties of the resulting thin films were characterized using x-ray diffraction, scanning electron microscopy (SEM) and UV–vis spectroscopy respectively. The structural study has proved that pure nanocrsytalline β-indium sulfide films were obtained at 300 and 400 °C regardless of the substrate nature, while higher growth temperature (500 °C) leads to the formation of pure indium oxide films. From the SEM images, it is derived that the surface morphology of the obtained films was independent to both growth temperature and substrate nature. The electronic structure of β-In2S3 was computed using density functional theory calculations. The optical properties of the obtained films such as energy band-gap, extinction coefficient, refractive index, dielectric constant and optical conductivity were investigated theoretically and experimentally. It was shown that these parameters were mainly controlled by the substrate type and the phase formed. The theoretical optical investigation was in full agreement with the experimental results. Oscillator energy, dispersion energy and Urbach energy were also estimated. Blue and violet PL emissions indicate the useful application of the obtained films as blue and violet light emitters.

Effect of high gamma radiations on physical properties of In2S3 thin films grown by chemical bath deposition for buffer layer applications

Abstract Polycrystalline In2S3 thin films have been grown on SnO2/glass substrates by chemical bath deposition technique and irradiated at different high gamma doses 3, 7, 15 and 40 kGy. X-ray diffraction, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), Spectrophotometer, Photoluminescence and Thermoluminescence were used to investigate physical properties of In2S3 thin films induced by gamma irradiation. After being irradiated, structural properties of In2S3 thin films have shown that preferred orientation has been moved from (4 0 0) plan at 2θ1 = 33.42° to a new created orientation at 2θ2 = 38.06° for 40 kGy gamma dose. EDS analysis has shown that atomic percentage (S/In) has been strongly varied for 40 kGy which indicate significant changes in stoichiometry. Thermoluminescence of irradiated In2S3 thin films has revealed a good sensitivity toward absorbed gamma dose. After irradiation, optical transmittance of In2S3 thin films has been increased from 50% to a maximum value of 70% in the visible range for 15 kGy dose. Band gap energy Eg has been slightly decreased. Other optical parameters such absorption and extinction coefficients, refractive index and permittivity have been determined. These experimental results show that gamma radiations can be used for tuning physical properties of In2S3 thin films for photovoltaic applications.

Impact of the annealing time on physical properties of sprayed In2S3 thin films

Indium sulfide thin films were deposited on preheated soda-lime glass substrates using spray technique over experiment optimum conditions (Ts = 340 °C, S/In = 2). The effect of annealing time on structural, morphological, optical and electrical properties of the films was investigated. X-ray diffraction spectra show that In2S3 films are polycrystalline with a cubic phase and preferentially oriented towards (400) for different annealing times. It is found that the film grain size increases from 39 to 49 nm when increasing the annealing time from 1 to 5 h. Both field emission scanning electron microscopy and atomic force microscopy images show that the surface morphology is strongly dependent upon the annealing time. Electron dispersive X-ray spectroscopy reveals that the film composition is not affected by the annealing. Raman spectroscopy analysis shows the predominance of active modes of β-ln2S3 films with annealing time. Optical band gap is found to vary in the range 2.38–2.63 eV for direct transitions. At room temperature, Hall effect measurements show that the mobility (µ) and the carrier concentration (nv) vary in the ranges 1.65–29.3 cm2 V−1 s−1 and 1.16 × 1017–2.82 × 1017 cm−3, respectively. Also, the electrical resistivity of the films is reduced from 14.47 to 1.65 Ω cm with increasing annealing time. The results are in good agreement with available literature and showed its future use in many optoelectronics devices.

Оптические и фотоэлектрические свойства тонких пленок GaS и гетероструктуры GaS/InSe

AbstractGaS thin films have been grown by the SILAR method, their structures have been analyzed, and their optical and photoelectric properties have been investigated. The internal structure of the samples obtained have been studied using X-ray diffraction (XRD) analysis, atomic force microscopy (AFM), energy-dispersive X-ray (EDX) spectroscopy, and scanning electron microscopy (SEM). The GaS band gap has been determined from the absorption spectrum. p -GaS/ n -InSe heterojunctions have been formed on the basis of GaS crystals and InSe thin films. Current–voltage, optical, photoelectric, and luminescence characteristics of p -GaS/ n -InSe heterojunctions have been experimentally investigated.

A straightforward chemical approach for excellent In2S3 electron transport layer for high-efficiency perovskite solar cells.

Perovskite solar cells (PSCs) have attracted significant attention in recent years owing to some of their advantages: high-efficiency, low cost and ease of fabrication. In perovskite photovoltaic devices, charge transport layers play a vital role for selectively extracting and transporting photo-generated electrons and holes to opposite electrodes. Therefore, it is very important to prepare high-quality charge transport layers using simple processes at low cost. As reported, In2S-based electron selective layers display excellent performance including high solar-cell efficiency and negligible hysteresis. In this study, a simple chemical method was developed to prepare In2S3 thin films as the electron selective layers in organic–inorganic hybrid perovskite photovoltaic devices to shorten the fabrication time and simplify the technology, which can provide a new avenue for a low-cost and solution-processed method. By optimizing the preparation conditions, it was demonstrated that In2S3 thin film prepared using our straightforward chemical approach have higher electron extraction efficiency and comparable efficiency compared with archetypical TiO2 as the electron transport layer (ETL) in perovskite photovoltaic device.

Pulsed-laser deposition of InSe thin films for the detection of thickness-dependent bandgap modification

Layer-structured InSe is one of the intensively studied two-dimensional monochalcogenide semiconductors for optical and electrical devices. Significant features of the InSe device are the thickness dependent bandgap modification resulting in a peak shift of photoluminescence and a drastic variation of electron mobility. In this study, by applying the pulsed-laser deposition technique, we investigated the optical and electrical properties of c-axis oriented InSe films with the thickness varying from a few to hundred nanometers. The energy at the absorption edge systematically shifts from about 3.3 to 1.4 eV with the increasing thickness. The InSe films on Al2O3(0001) are highly resistive, while those on InP(111) are conductive, which probably originates from the valence mismatch effect at the interface. The electron mobility of the conducting charge carrier at the interface of InSe/InP is enhanced in thicker samples than the critical thickness of about 10 nm, corresponding to the bandgap modification characterized by the optical measurement. Therefore, the substrate and the film thickness are critically important factors for the materialization of InSe optical and electrical device applications.

Effect of annealing on the physical properties of thermally evaporated In2S3 thin films

The structural, compositional, morphological and optical properties of In2S3 thin films, prepared by thermal evaporation technique and annealed in sulfur ambient at different temperatures have been investigated. The grazing incident X-ray diffraction patterns have indicated polycrystalline form and predominantly cubic structure of annealed In2S3 films. The scanning electron microscopy revealed textured surface with uniformly distributed grains and the grain size increased with increase of annealing temperature. The optical parameters of the films have been determined using conventional transmission and reflection spectra as well as from surface photovoltage measurements.

Nickel doping effect on the structural and optical properties of indium sulfide thin films by SILAR

Abstract Undoped and nickel doped indium sulfide (In2S3:Ni) thin films have been deposited on indium tin oxide (ITO) coated glass substrates by successive ionic layer adsorption and reaction (SILAR) method. The doping concentration of Ni has been adjusted as 4%, 5% and 6% (in molar ratio of nickel ions to indium ions). The effects of Ni doping on the structural, morphological, compositional and optical properties of the In2S3 thin films are investigated. The x-ray diffraction patterns show that deposited film has cubic structure with amorphous nature of In2S3 and its crystallinity deteriorates with increasing doping concentration. The SEM measurements show that the surface morphology of the films is affected from the Ni incorporation. The direct band gap of the films decreases from 2.33 eV to 1.61 eV with increasing Ni dopant. Energy dispersive x-ray spectroscopy (EDS) has been used to evaluate the chemical composition and shown that S/(Ni+In) ratio in films decreases from 1.18 to 0.40 with Ni content. Optical properties of the films have been performed by a UV-Vis spectrophotometer. The direct band gap of the films decreases from 2.33 eV to 1.61 eV with increasing Ni dopant. Moreover, optical parameters of the films such as refractive index (𝑛), extinction coefficient (k), real (ε 1) and imaginary (ε 2) parts of dielectric constant have been determined by using absorbance and transmittance spectra. The investigations showed that the Ni doping has a significant effect on the physical properties of SILAR produced In2S3 thin films.

Effect of silver doping on structural and optical properties of In2S3 thin films fabricated by chemical pyrolysis

Silver doped indium sulphide thin films (In2S3:Ag) were deposited by spray pyrolysis technique on glass substrates at temperature 350 °C. The films were prepared by varying the Ag:In ratio from 0% to 8%. The effect of silver concentration on structural and optical properties of In2S3:Ag thin films have been studied in detail using X-ray diffraction (XRD) and ultra violet, visible and near infra red (UV–Vis–NIR) transmittance spectroscopy. The X-ray diffraction analysis showed that the prepared layers are polycrystalline and crystallize in a β-In2S3 cubic structure and the size of the crystallites varies between 16 and 20 nm. UV–Vis–NIR spectroscopy measurements revealed that the optical transmittance of the films exceeds 90% in the visible and near infrared region and also the direct band gap energy of the fabricated thin film samples increases with doping from 2.63 to 2.97 eV. The roughness values evaluated are almost constant for different doping concentration.

Solution-Based Processing of Optoelectronically Active Indium Selenide.

Layered indium selenide (InSe) presents unique properties for high-performance electronic and optoelectronic device applications. However, efforts to process InSe using traditional liquid phase exfoliation methods based on surfactant-assisted aqueous dispersions or organic solvents with high boiling points compromise electronic properties due to residual surface contamination and chemical degradation. Here, these limitations are overcome by utilizing a surfactant-free, low boiling point, deoxygenated cosolvent system. The resulting InSe flakes and thin films possess minimal processing residues and are structurally and chemically pristine. When employed in photodetectors, individual InSe nanosheets exhibit a maximum photoresponsivity of ≈5 × 107 A W-1 , which is the highest value of any solution-processed monolithic semiconductor to date. Furthermore, the surfactant-free cosolvent system not only stabilizes InSe dispersions but is also amenable to the assembly of electronically percolating InSe flake arrays without posttreatment, which enables the realization of ultrahigh performance thin-film photodetectors. This surfactant-free, deoxygenated cosolvent approach can be generalized to other layered materials, thereby presenting additional opportunities for solution-processed thin-film electronic and optoelectronic technologies.

Low-temperature growth of γ phase in thermally deposited In2Se3 thin films

ABSTRACTIn the present report, we have studied the structural and optical change in the In2Se3 thin films prepared by the thermal evaporation method, deposited on a glass substrate and annealed at 250°C. Both the structural and optical studies revealed the formation of γ-In2Se3 phase on annealing at such low temperature as 250°C which is not observed before. Raman analysis indicates that the as-prepared film consists of both α and γ-In2Se3 phases and the annealed film contains only γ-In2Se3 phase. The absorption mechanism in the studied film follows the direct allowed transition. The optical band gap is found to be decreased with annealing due to the increase in the width of localized states near to the band edges. Transmittance is found to be decreased and the absorption is increased with annealing due to the change in the film density which enhances its suitability for solar cell applications.

Dielectric dispersion in InSe/CdS bilayers

In the current study, the effect of the amorphous InSe thin film substrate on the structural, optical and dielectric properties of CdS are investigated. The structural analysis of the bilayers indicated a strained growth of CdS onto InSe leading to decrease in grain size and increase in the dislocation density. The optical measurements have shown that the InSe/CdS exhibits two direct allowed transitions energy band gap values of 2.04 and 1.38 eV, in the high and low absorption regions, respectively. On the other hand, the detailed analysis of the dielectric spectra for the InSe, CdS and InSe/CdS layers has shown that the presence of the InSe substrate significantly improves the optical conduction parameters. Particularly, the Drude-Lorentz modeling for these dielectric systems revealed a drift mobility value of 329 cm2/V for the InSe/CdS bilayer. The deposition of the CdS onto InSe is also observed to shift the plasmon frequency of CdS from 2.49 to 0.77 GHz. The general features of the InSe/CdS as plasmon cavities are promising as it shows its usability for production of optoelectronic devices that exhibit high performance at very high frequencies.

Ethanol sensing properties of sprayed β-In2S3 thin films

This work reports on the integration of In2S3 material for use as an alcohol sensor. In2S3 thin films were deposited on glass substrates by spray pyrolysis technique. The morphology and microstructure of the obtained samples were characterized by XRD, SEM, TEM and EDX methods. The response to ethanol vapor at different concentrations was measured in the range of operating temperatures 250 °C–400 °C using DC electrical characterization. The In2S3 based sensor showed good sensitivity towards ethanol at optimal working temperature of 350 °C. The sensing mechanism of In2S3 semiconductor was developed on the bases of the reaction between the reducing ethanol vapors with the chemisorbed oxygen. The sensor rapidity, selectivity, stability and reproducibility were also studied.

Special Features of the Optical Absorption and Photoconductivity of Indium Monoselenide Upon Laser Excitation

The successive ionic layer adsorption and reaction (SILAR) method is used to prepare InSe thin films and InSe nanoparticles. Shapes and sizes of the obtained nanoparticles are investigated using a scanning electron microscope and an atomic force microscope. The main parameters of the examined structures, nanoparticle sizes (4–20 nm), and band gap (Е g = 1.60 eV) for nanoparticles with the least sizes are determined. Superfast (1.5·10-8 s) photocurrent relaxation and stimulated emission with line half-width of 8 A have been observed upon exposure to laser radiation.

Photoluminescence in Spray Pyrolysis Deposited β-In2S3 Thin Films

Spray pyrolysis deposited In2S3 thin films exhibit two prominent photoluminescent emissions. One of the emissions is green in color and centered at around ∼ 540 nm and the other is centered at around ∼ 690 nm and is red in color. The intensity of the green emission decreases when the films are subjected to annealing in air or vacuum. The intensity of red emission increases when films are air annealed and decreases when vacuum annealed. Vacuum annealing leads to an increase in work function whereas air annealing leads to a decrease in work function for this thin film system relative to the as deposited films indicating changes in space charge regions. Surface photovoltage analysis using a Kelvin probe leads to the conclusion that inversion of band bending occurs as a result of annealing. Correlating surface contact potential measurements using a Kelvin probe, x-ray photoelectron spectroscopy and photoluminescence, we conclude that the surface passivation plays a critical role in controlling the photoluminescence from the spray pyrolysis deposited for In2S3 thin films.

Preparation of InSe Thin Films by Thermal Evaporation Method and Their Characterization: Structural, Optical, and Thermoelectrical Properties

The indium selenium (InSe) bilayer thin films of various thickness ratios, InxSe(1-x) (x = 0.25, 0.50, 0.75), were deposited on a glass substrate keeping overall the same thickness of 2500 Ǻ using thermal evaporation method under high vacuum atmosphere. Electrical, optical, and structural properties of these bilayer thin films have been compared before and after thermal annealing at different temperatures. The structural and morphological characterization was done using XRD and SEM, respectively. The optical bandgap of these thin films has been calculated by Tauc’s relation that varies within the range of 1.99 to 2.05 eV. A simple low-cost thermoelectrical power measurement setup is designed which can measure the Seebeck coefficient “S” in the vacuum with temperature variation. The setup temperature variation is up to 70°C. This setup contains a Peltier device TEC1-12715 which is kept between two copper plates that act as a reference metal. Also, in the present work, the thermoelectric power of indium selenide (InSe) and aluminum selenide (AlSe) bilayer thin films prepared and annealed in the same way is calculated. The thermoelectric power has been measured by estimating the Seebeck coefficient for InSe and AlSe bilayer thin films. It was observed that the Seebeck coefficient is negative for InSe and AlSe thin films.