In2S3 Thin Films Research Articles

Photoelectrodes with Enhanced Carrier Generation and Collection Through Optical Simulation and Materials Engineering

AbstractThe efficiency of solar‐fuel conversion in photoelectrochemical (PEC) systems is hindered by significant losses of photons and photocarriers within the photoelectrodes. This study introduces an innovative ITO@In2S3 core‐shell nanowire structure designed to overcome these challenges through cutting‐edge materials engineering and sophisticated simulation techniques. Optical modeling and finite element simulations highlight the conflict between photocarrier generation and collection in planar In2S3 thin films and demonstrate how the core‐shell nanowire geometry can significantly enhance light absorption. The developed ITO@In2S3 nanowire photoanodes achieve a photocurrent of 11.3 mA cm−2 at 1.23 V versus RHE, which is nearly five times greater than that of planar ITO/In2S3 thin films. Characterization techniques, including UV–vis absorption and charge separation efficiency measurements, confirm the enhanced light absorption and improved carrier collection facilitated by broadening the optical absorption range and reducing carrier transport distances. This research not only deepens the understanding of the dynamics within thin‐film photoelectrodes but also paves the way for the development of more efficient technologies for solar fuel conversion.

Effect of substrate temperature on In2S3 thin films using nebulizer spray pyrolysis method for photodetector applications

In this work, Indium Sulfide (In2S3) thin films were prepared using an economical nebulizer spray pyrolysis technique by various substrate temperatures from 250 °C to 375 °C in steps of 25 °C to evaluate their photo sensing properties. X-ray diffraction (XRD) patterns confirm the presence of In2S3 with face centered cubic structure for all substrate temperatures. The densely packed small spherical grain-sized particles were observed for In2S3 films deposited at 350 °C using Field emission scanning electron microscope (FESEM) analysis. The optical bandgap values were decreased from 3.16 eV to 2.28 eV, with increment in coating temperatures from 250 °C to 350 °C. The high intensity Photoluminescence (PL) peak is observed at 480 nm for the film coated at 350 °C is due to higher rate of electron–hole pair recombination. The photo sensing analysis revealed that the In2S3 thin films deposited at 350 °C, has the maximum responsivity (R) of 9.09 × 10−2 A W−1, detectivity (D*) of 8.25 × 1010 Jones, and external quantum efficiency (EQE) of 21.2%. Increasing the substrate temperature results in a significant enhancement of photo sensing characteristics.

A novel photoelectrochemical based water splitting and uric acid biosensing using PLD grown In2Se3 thin films

By altering the deposition pressure during the film growth process using the pulsed laser deposition (PLD) technology, indium selenide (In2Se3) thin films have been optimized to produce their distinct phases. The phase purity, optical and morphological studies were carried out using XRD, Raman spectroscopy, XPS, UV–visible spectroscopy, AFM and FESEM measurements. A high absorption in the visible region is observed for In2Se3 thin films with suitable band edges for hydrogen evolution. Photoelectrochemical (PEC) activity for In2Se3 photoelectrodes having various phases was analyzed based on CV and I-t response. A good charge transport characteristics were observed using the EIS measurements on PLD grown In2Se3 thin films. The Mott–Schottky analysis for the charge carrier density, flat band potential, and depletion layer width was performed for the deposition pressure dependent phase formation and high performance for PEC water splitting conversion efficiency of 0.48 %, 0.57 % and 0.98 % corresponding to α-In2Se3, β-In2Se3 and γ-In2Se3 were observed, respectively. The as prepared In2Se3 thin films were employed for the detection of Uric Acid (UA) using the cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry. The high sensitivity (0.38 mA/mM), selectivity and repeatability of the prepared biosensor demonstrates In2Se3 as potential candidate for the PEC based water splitting and biosensing application without the presence of an external mediator and can work in the self-powered mode.

High-quality InSe thin films and PbSe/InSe/PbSe barrier detector by thermally evaporated deposition

High-quality InSe thin films and PbSe/InSe/PbSe barrier detector by thermally evaporated deposition

Fabrication of Bi-doped In2S3 thin films for highly sensitive UV photodetector applications

Fabrication of highly sensitive, high-speed photodetectors, especially using cost-effective and less toxic materials, has attracted continuous attention due to their outstanding advantages. In this report, we present different properties of Bi-doped (0,1, 3, and 5 wt%) In2S3 thin films for UV photodetectors. Bi-doped (0, 1, 3, and 5 wt%) In2S3 thin films were coated on glass substrates at a temperature of 350 °C using a low-cost nebulizer spray pyrolysis method. X-ray diffraction XRD analysis confirmed the cubic phase β-In2S3 for all the deposited films and high crystallinity is obtained for 1 wt% Bi-doped film. The presence of densely packed grains in 1 wt% Bi-doped In2S3 thin film and also small grains observed for undoped In2S3 sample is evident form morphology studies. Bi doping has caused an enhancement of optical absorption and incorporation of 1 wt% of Bi3+ into In2S3 has shifted the optical band gap from 2.87 to 2.78 eV. Current − Voltage characteristics and Current–Time characterization are used to know the key parameters of the photodetectors. Among all fabricated photodetectors, the In2S3 thin film doped with 1 wt% Bi showed superior photodetector performance with calculated Responsivity (R), Detectivity (D*), and External quantum efficiency (EQE) values of 0.65 AW−1, 15 × 1010 Jones, 125 % respectively. Transient photo-response analysis showed low rise and fall time of 3.21 and 3.78 s respectively for the 1 wt% Bi-doped sample. Optimally doped In2S3: Bi (1 wt%) thin film is most suited to fabricate photo sensing-based optoelectronic devices in UV region of the spectrum.

Investigation of the physico-chemical properties of In2S3 powder synthesized via solid-state reaction and In2S3 thin films prepared through thermal evaporation

In this study, we examined the physico-chemical properties of In2S3 powder produced using the solid-state reaction and of the In2S3 thin film obtained using the thermal evaporation technique. Thermally evaporated In2S3 thin films were subjected to vacuum annealing to study the impact of heating on the structural, morphological and optical properties of the samples. According to the X-ray diffraction analysis, the microstructure of as-grown thin films were an amorphous in nature which transformed into polycrystalline structure after annealing at T≥250 °C. This polycrystalline structure suggests the formation of the β-In2S3 phase with a tetragonal and/or cubic crystal structure. In addition, the energy dispersive spectroscopy analysis revealed that all samples show a slight excess of indium and a deficit of sulfur, compared to the stoichiometric ratios. Moreover, surface micrographs recorded by atomic force microscopy showed an increase in surface roughness after annealing. Optically, the transmittance spectra, T(λ), illustrated a high transmittance average value,∼70 %, while the reflectance spectra, R(λ), showed an average value of 25 % in the visible and NIR region. It appeared that heat treatment had no significant impact on the T and R spectra. The optical dispersion parameters of the treated samples were also studied. The direct and indirect allowed bandgap transitions values of all samples were found to ranging from 1.75 to 2.48 eV and from 1.80 to 2.38 eV, respectively. Such observation shows that the bandgap increased with annealing temperature. Electrically, n-type conductivity for In2S3 films annealed at 250 °C was recorded.

Influence of Sn doping on particle cluster to rock-plate growth of nano-structured In2S3 thin films by nebulized spray pyrolysis technique

ABSTRACT The Nebulized Spray Pyrolysis (NSP) process has created Sn-doped In2S3 thin films for various molar percentages on micro glass substrates. The structural, optical, morphological, and electrical characteristics of the thin films have all been studied. A cubic phase had formed in each of the deposited films, according to an X-ray diffraction analysis. The average transmittance of the films ranged from 75 to 96%, while the bandgap energies for direct permitted transitions varied from 2.32 to 2.77 eV. The Scanning Electron Microscopy (SEM) images showed the rock-plate type nanoparticles grown over the surface of the glass plates. The Hall effect study revealed the n-type conductivity and with a 3 mol% Sn-doped In2S3 thin film exhibited a carrier concentration of 17.36 × 1018 cm−3 with the lowest resistance of 21.6 Ω-cm.

PHOTOTHERMAL DEFLECTION ANALYSIS OF β-In2S3 THIN FILMS: THE EFFECT OF S/In MOLAR RATIOS

[Formula: see text]-In2S3 thin films ([Formula: see text], 2 and 4) were prepared using the pneumatic spray pyrolysis (PSP) route to analyze the effect of the S/In ratio on the physical properties. These properties were conducted using the photothermal deflection spectroscopy (PDS) method. The PDS signal amplitudes as a function of wavelength show multiple reflections which appear for all prepared In2S3 films. Such multiple reflections indicate homogeneity and high crystalline quality of the films. The deduced values of the optical band gap vary in the range 2.55–2.65[Formula: see text]eV. The highest thermal diffusivity is obtained for [Formula: see text]. The product ([Formula: see text]) is found in order of 10[Formula: see text][Formula: see text]cm[Formula: see text]/V. The estimated carrier diffusion lengths are 0.06, 0.11 and 0.09[Formula: see text][Formula: see text]m for films corresponding to [Formula: see text], 2 and 4, respectively. Defect absorption in [Formula: see text]-In2S3 films is also investigated by PDS. Five absorption peaks are observed. These absorption peaks contain defect information in the band gap. Hence, this work evidences that [Formula: see text]-In2S3 is a multi-functional material that can be used in optoelectronic, photovoltaic and visible-irradiation photocatalyst applications.

Optimizing Photovoltaic Efficiency Through Di-Indium Tri-Selenide Thin Film Solar Cells

This study focuses on investigating the photovoltaic efficiency of chemically deposited In2Se3 thin films for solar energy conversion. Thin film solar cells have several advantages, including reduced material usage, cost-effectiveness, and the potential for improved efficiency. Our research specifically explores the viability of chemically deposited In2Se3 thin films for converting solar energy into electrical energy through chemical processes. The photovoltaic (PV) cell configuration consists of In2Se3 thin films as the photoanode and a sulfide-polysulphide (0.15 M) solution as the electrolyte. The structure of the cell is n-In2Se3 | NaOH (0.15 M)+ S (0.15 M)+Na2S (0.15 M) |C (graphite). To comprehensively analyze the performance of the thin films, we employ various characterization techniques. These include studying the current-voltage characteristics under both dark and light conditions, capacitance–voltage in the dark, barrier height measurements, power output analysis, photo response evaluation, and spectrum response examinations. Through these analyses, we have discovered that In2Se3 exhibits n-type conductivity. Noteworthy results include a junction ideality factor of 3.43, a flat band potential of −0.680 V, and a barrier height of 0.193 eV. The power output characteristics provide crucial insights into the performance of the PV cell. We measured the open circuit voltage, short circuit current, fill factor, efficiency, and photo response lighted ideality factor, which were found to be 320 mV, 25.4 μA, 36.46%, 0.69%, and 2.56, respectively. This research significantly contributes to our understanding of the photovoltaic efficiency of di-indium tri-selenide thin film solar cells. It offers valuable insights for optimizing their performance in solar energy conversion applications.

Fast crystallization of InSe thin films via pulsed laser welding technique and effect of crystallinity on the optical and dielectric properties

In the current study the crystalline phase of indium selenide thin films which were grown by the thermal evaporation technique is achieved via pulsed laser welding technique (PLW) in a second. The films crystallinity is achieved under various welding conditions including the pulse width ( PW ), repetition frequency ( fr ) and pulse diameter ( d ). The optimum parameters for obtaining well crystalline phase are PW=1.0 ms, fr=10 Hz and d= 1.0 mm. PLW induced crystallinity showed preferred structure relating to monoclinic phase of InSe. Compositionally while amorphous films exhibited In2Se3 chemical structure, crystalline ones preferred InSe phase. Associated with this type of crystallinity, direct and indirect energy band gap values of 2.32 eV and 3.12 eV are determined. The crystalline films showed lower dielectric constant value accompanied with higher optical conductivity and higher terahertz cutoff frequency in the infrared range of light. In addition the dielectric dispersion spectra were treated using Drude–Lorentz model to read the optical conductivity parameters for the PLW assisted crystalline InSe terahertz resonators. The treatment showed that the crystallinity of the films resulted in improved free carrier density, longer relaxation times at femtosecond level, larger plasmon frequencies and higher drift mobility values. These features together with the response of terahertz cutoff frequency to IR excitations make crystalline InSe thin films promising for optoelectronic and terahertz technology applications.

Doping induced multiferroicity and quantum anomalous Hall effect in α-In2Se3 thin films

In flatband materials, the strong Coulomb interaction between electrons can lead to exotic physical phenomena. Recently, α-In2Se3 thin films were found to possess ferroelectricity and flat bands. In this work, using first-principles calculations, we find that for the monolayer, there is a Weyl point at Γ in the flatband, where the inclusion of the spin–orbit coupling opens a gap. Shifting the Fermi level into the spin–orbit gap gives rise to nontrivial band topology, which is preserved for the bilayer regardless of the interlayer polarization couplings. We further calculate the Chern number and edge states for both the monolayer and bilayer, for which the results suggest that they become quantum anomalous Hall insulators under appropriate dopings. Moreover, we find that the doping-induced magnetism for the In2Se3 bilayer is strongly dependent on the interlayer polarization coupling. Therefore, doping the flat bands in In2Se3 bilayer can also yield multiferroicity, where the magnetism is electrically tunable as the system transforms between different polarization states. Our study, thus, reveals that multiferroicity and nontrivial band topology can be unified into one material for designing multifunctional electronic devices.

Investigation of In2SexOy/In2Se3/Si dual-junction photodiode for self-powered broadband photodetection

We report a dual-junction strategy for fabricating a high-performance In2SexOy/In2Se3/Si heterojunction photodiode by oxidizing the epitaxial In2Se3 thin films. The device exhibits a suppressed dark current (4.2 × 10−11 A) and enhanced photocurrent at zero bias, benefiting from the double built-in electric fields. Consequently, it demonstrates excellent and uniform self-powered broadband (255–1050 nm) photodetection performance with the typical responsivity of several hundred mA/W, and detectivity of over 5 × 1011 Jones. Moreover, a fast response speed with a response time of 0.20 ms is achieved. Our investigation offers a potential route to construct full-spectrum photodetectors.

In2S3 thin films with potential use as window layers in photovoltaic devices

In this study, we use the Haacke’s figure of Merit (FOMH) as a valuable parameter for determining suitable Indium Sulphide thin films among a set of samples processed with different deposition parameters, in order to use them as window layers in the usual configuration of photovoltaic devices. Two sets of In2S3 thin films were deposited by radiofrequency (RF) magnetron sputtering technique with an average thickness around 90 nm and using different deposition parameters. One set of samples was processed using different RF power in the range of 75–250 W at room temperature, the second set was obtained using different substrate temperatures 24 °C–350 °C keeping a constant RF power at 75 W. The FOMH consider optical and electrical properties of In2S3 thin films in order to evaluate the feasibility of the thin film to be used as a window layer in photovoltaics devices. The In2S3 thin films processed by RF-Sputtering were analyzed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Ultraviolet-Visible spectroscopy, Raman spectroscopy, x-ray diffraction (XRD) and four-probe method. The In2S3 thin films had a high optical transmittance of 84% and the energy band gap values of the films decreased from 2.48 to 2.38 with the increase in substrate temperature and deposition power. The estimated grain size decreasing from 65 to 45 nm as the RF power increased. Additionally, the crystallinity of the selected In2S3 thin films was analyzed by Raman and XRD and showing that the cubic and tetragonal β-In2S3 phases can coexist in the films. The In2S3 thin films showed resistivity vales around Higher values of FOMH were obtained for In2S3 thin films processed at 75 W, 250 W, 100 °C and 300 °C, therefore these layer are feasible candidates to be used as window layers in photovoltaic devices.

Isopropanol sensor based on sprayed In2S3 thin film using linear discriminant analysis for real-time selectivity.

Metal sulfides have been studied for their high performance as new sensitive materials for gas detection. These material innovations contribute significantly to the development of more sensitive, stable and specific conductivity sensors, opening the way to new applications in detecting gases at low concentrations. Hence, this work reports on the sensing performance of In2S3 for isopropanol detection. Numerous VOCs, such as ketones, alcohols, and aldehydes, serve as cancer biomarkers. Notably, isopropanol, as a biomarker, shows a substantial increase (20-1007 ppb) in lung cancer patients, suggesting its potential as an early diagnostic criterion. To explore this, we fabricated a thin film of In2S3 onto a platinum interdigitated silicon dioxide substrate by simple and low-cost spray pyrolysis technology. Structural and morphological analyses via XRD, MEB, AFM, and TEM were conducted on the prepared samples. Isopropanol vapor response was assessed within a controlled temperature range of 250 °C-450 °C. The In2S3-based sensor demonstrated notable sensitivity (0.034 ppm-1), maintained stability over three weeks, and reliably detected isopropanol activation. In2S3 emerges as a promising candidate for detecting isopropanol, with a limit of detection (LOD) of 162 ppb. In this work, seven VOCs, including isopropanol, ethanol, methanol, butan-1-ol, formaldehyde, toluene, and acetone, were evaluated. Cross-responses among these VOCs were observed, indicating a lack of assured sensor selectivity. However, isopropanol recognition was achieved by employing linear discriminant analysis (LDA) on pertinent features derived from transient current change measurements. As a result, the sensor's sensitivity enables the deduction of the isopropanol concentration.

In2S3 Thin Films via Open‐Air Chemical Vapor Deposition Using Indium‐Diethyldithiocarbamate: Deposition and Characterization

Cadmium‐free materials for the buffer layer of thin‐film solar cells and their low‐cost manufacturing methods have been of great interest in the solar industry. In this study, diindium trisulfide (In2S3) is investigated as an alternative buffer layer material: In2S3 thin film was deposited at atmospheric pressure utilizing open‐air chemical vapor deposition (CVD). Indium‐diethyldithiocarbamate (In‐DDTC) is used as the only solid precursor. The deposition conditions, crystal structure, optical properties, and electrical properties of In2S3 thin films are studied. The solid source temperature is found to affect the morphology, whereas the substrate temperature affected the growth rate and the sulfur‐to‐indium ratio of the films. X‐Ray diffraction and Raman scattering measurements suggested that the prepared films consist of β‐In2S3 and show a strong (103)‐plane orientation under suitable deposition conditions. The films exhibited indirect and direct transitions around 2.0 eV and 2.7–2.8 eV, respectively. The thin films showed n‐type conduction, with the lowest resistivity of 28.6 Ω cm. Overall, In2S3 thin films prepared via open‐air CVD are promising alternative buffer layer materials, which are expected to contribute to the realization of low‐cost and environmentally friendly thin‐film solar cells.

Formation, Enhanced Crystallization, Optical Absorption and Electrical Conduction in Copper Indium Selenide Thin Films Prepared via Pulse Laser Welding Technique

AbstractIn this study, thin films of CuInSe2 (CIS) are expeditiously fabricated within 1 s utilizing the pulsed laser welding (PLW) technique. Preceding the PLW process, thin films of InSe (500 nm) are coated with Cu nanosheets of 60 and 120 nm thicknesses using vacuum coating systems. The optimal PLW parameters leading to the formation of CIS films include a pulse width of 1.0 ms, a spot diameter of 2.0 mm, and a repetition frequency of 10 Hz. The resulting CIS films exhibited a well‐crystalline cubic structure with lattice parameters of 5.265 Å. Surface morphology analyses revealed the preferential formation of porous films with varying stoichiometry, a characteristic that can be manipulated by adjusting laser welding parameters. The energy band gap and room temperature electrical conductivity display values of 1.80 eV and 2.06 × 10−5 (Ωcm)−1, respectively. Cu‐rich samples exhibit a wider energy band gap of 1.94 eV and lower electrical conductivity values of 4.78 × 10−7 (Ωcm)−1. The CIS film demonstrates n‐type conductivity attributed to the formation of donor levels centered at 0.24 and 0.10 eV. This study presents an ultrafast method for fabricating CIS films with physical properties compatible with those produced using traditional methods.

Enhancing photocatalysis through annealing: Unveiling the role of physical properties in photocatalytic behavior

Using spray pyrolysis, silver-doped In2S3 thin films were deposited on pre-heated glass substrates, with varying doping concentrations. Subsequently, these films underwent vacuum annealing at 400 °C for a duration of 2 h. A comprehensive study of their structural, morphological, and optical properties was conducted, revealing homogeneous, compact, crack-free films with polycrystalline tetragonal-phase of In2S3. Among the set of the analyzed films the best parameter values, including crystallite size, dislocation density, micro-strain, grain size, and root mean square (RMS) roughness, were achieved when maintaining a Silver-to-indium (|Ag|/|In|) ratio of 4 % in the precursors for both as-deposited and annealed samples. The annealing process had a discernible impact on the grain size distribution, resulting in a significant increase in crystallite and grain size, along with RMS roughness, for most doped films. The optical analysis of these films unveiled their transparency in the visible and near-infrared regions, coupled with substantial absorption in the UV region. Higher Ag concentration in the as-deposited films led to an increased band gap energy in the annealed samples. The roughness peaked at |Ag|/|In| = 4 %, resulting in a noteworthy enhancement of photocatalytic activity, achieving 95 % photodegradation of a methylene blue aqueous solution. This underscores the critical role of surface properties in determining performance. Future research intends to explore other applications for these thin films, including potential usage in gas sensors, capitalizing these films' promising characteristics.

Improving FTO/ZnO/In2S3/CuInS2/Mo solar cell efficiency by optimizing thickness and carrier concentrations of ZnO, In2S3 and CuInS2 thin films using Silvaco-Atlas Software

Optimization of optical and electrical properties of active semiconducting layers is required to enhance thin film solar cells' efficiency and consequently became the cornerstone for sustainable energy production. Computational studies are one of the ways forward to optimize solar cells’ characteristics. In this study, Silvaco-Atlas, a powerful software that excels in both 2D and 3D electrical simulations of semiconductors has been used for the simulation in order to investigate the solar cell properties. The architecture of the solar cell simulated was FTO/ZnO/In2S3/CuInS2/Mo. This study aims to optimize solar cell efficiency by optimizing film thicknesses and carrier concentrations via simulation. The designed solar cell was exposed to the presence of a sun spectrum of AM1.5 from a 1kW/m2 incident power density at 300K. The thickness values of the window (ZnO), absorber (CuInS2) and buffer (In2S3) layers were varied to record a solar cell's optimum thickness. The resulting FTO/ZnO/In2S3/CuInS2/Mo solar cell formed by simulation is presented. The best efficiency and fill factor of the solar cell simulated were found to be 41.67% and 89.19%, respectively. The recorded values of current density and the open circuit voltage of the cell were 40.33mA/cm2 and 1.15 V, respectively. Additionally, the maximum power of the simulated solar cell device was 41.68 mW. Optimization results revealed that the most efficient cell found was made up of a window layer with a thickness of 0.03μm, an absorber layer with a thickness of 6.0μm and a buffer layer with a thickness of 0.2μm. The optimized carrier concentration of ZnO, In2S3 and CuInS2 was respectively 1e21 cm-3, 1e20 cm-3, 3e18 cm-3 and the optimized Al-doped ZnO value was 1e25 cm-3. The Absorption spectra indicated that the solar cell's peak absorption occurs between 350 nm and 1250 nm and presented a good external quantum efficiency (EQE) of around 84.52% to 92.83% which indicates good efficiency in the visible domain. This performance is attributed to the transparency of FTO, ZnO and good absorption of In2S3 and CuInS2 thin films.

Improved photo sensing behavior of the terbium doped In2S3 thin films synthesized by spray pyrolysis technique

In the present work, undoped In2S3 and varying concentrations of Tb (1, 2, 3, 4 & 5 wt%) doped In2S3 thin films were synthesized using the economical and nebulizer spray pyrolysis technique for studying their photosensing characteristics at room temperature. X-ray diffractometer (XRD) studies showed the diffraction pattern of the thin films exhibits a cubic- β phase of In2S3 and the highest crystallite size of 61 nm was observed for the In2S3: Tb (2wt%) thin film. The morphological & elemental analysis showed that all the synthesized thin films exhibit homogeneous non-uniform crystal morphology with the existence of S, In, Tb compounds with their distinct composition. From Ultraviolet-Visible(UV–vis) studies, all the prepared thin films exhibit maximum absorption in the UV region with a minimum bandgap of 2.85 eV for the In2S3:Tb (2wt%) thin film. Also, the Photoluminescence (PL) spectra showed that the In2S3:Tb (2wt%) thin film possesses two large intense emission peaks around ∼470 nm (Yellow) and 530 nm (green). Finally, the photo sensing studies showed that the fabricated In2S3:Tb (2wt%) thin film photodetector showed better photocurrent, Responsivity (R), Detectivity (D*), External Quantum Efficiency (EQE), Response/Recovery time values of ∼12.5 μA, 0.296 AW−1, 7.75 × 1010 Jones, 60%, 2.9/3.6 s, respectively indicating the device better suitable for commercial photodetector application.

Effects of sputtering pressure and annealing temperature on the characteristics of indium selenide thin films

Indium selenide is a significant two-dimensional lamellar semiconductor with excellent physical properties whose enormous potential utilization in optoelectronic devices has been practically hindered by the lack of suitable thin film deposition techniques. Herein, γ-In2Se3 thin films were successfully fabricated from an InSe-target via magnetron sputtering combined with subsequent annealing process. The effects of sputtering pressure and annealing temperature on the characteristics of as-deposited thin films were investigated. The x-ray diffraction (XRD) patterns reveal that the pristine thin films are amorphous in nature, whereas transform into polycrystalline and are identified as γ-In2Se3 phase after annealing treatment. The growth mechanism of as-deposited layers combines a two-dimensional lateral growth and a three-dimensional island growth. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) images indicate that all the samples show uniform and compact structures with no evident holes and crevices. The UV–vis-NIR spectrophotometer was employed to measure the optical transmittance and band gap of the synthesized thin films. The results show an obvious decrease in the band gap from 2.56 eV to 1.88 eV with annealing temperature increased from 400 °C to 600 °C, respectively. In addition, the difficult reasons for preparing monophase InSe thin films by magnetron sputtering method were discussed. These intriguing findings in this study may shed light on the growth of indium selenide thin films with well-crystallized and high quality.