Direct Vapour Transport Research Articles

Copper Intercalation Effect on Thermoelectric Performance of Pristine Tin Selenide

AbstractPristine tin selenide (SnSe) and copper (Cu) doped SnSe single crystals are grown by direct vapour transport technique. The energy dispersive X‐ray, X‐ray diffraction and Raman spectroscopic analysis of grown crystals show preferred stoichiometry having a single phase othorhombic SnSe. The electrical conductivity of SnSe and Cu doped SnSe are 24.24 and 106.06 S m−1 at 310 K respectively which increase as temperature increases. Carrier concentration of grown single crystals are evaluated by the Hall effect. Lattice thermal conductivity of pristine SnSe is 0.61 W mK−1, that decreased by copper doping to 0.44 W mK−1 at 310 K and for both the crystals it shows decrement as temperature increases to 483 K. Seebeck coefficient of the grown SnSe and Cu doped SnSe are positive and obtained values are 536.44 and 492.90 µV K−1 respectively at 310 K that confirm the p‐type semiconducting nature. Power factor, Figure of merit and thermoelectric compatibility factor of grown pristine SnSe is 0.25 × 108 µV mK−2, 0.005 and 0.02 Volt−1 respectively and shows improvement in Cu doped SnSe, i.e., 0.08 × 108 µV mK−2, 0.017 and 0.07 Volt−1 respectively at 310 K. This shows Cu doping in SnSe makes it an effective thermoelectric device contender.

Enhanced photocatalytic performance of two-dimensional NixRe1-xSe2 (x = 0 & 0.25) crystalline material: Exploring its potential as a high-efficiency catalyst

Water pollution, stemming primarily from dye effluent discharge in urban and industrial zones, remains a critical environmental issue. Photocatalysis emerges as a promising eco-friendly, cost-effective, solar-dependent, and recyclable solution. This study synthesizes Ni0.25Re0.75Se2 via a simple Direct Vapour Transport (DVT) technique, exploring the impact of doping on ReSe2's structural, optical, and photocatalytic properties. Characterization techniques (PXRD, FESEM, EDAX, Raman spectroscopy, UV–visible absorbance spectroscopy, XPS) were employed for analysis. Photocatalytic experiments with organic dyes like Methylene Blue (MB), Acridine Orange (AO), Crystal Violet (CV) demonstrated efficient AO dye degradation (95.67 %) in 60 min using Ni0.25Re0.75Se2, showcasing effective catalytic properties under 20W LED bulb. Trapping experiments identified hydroxyl radicals and holes as pivotal for AO dye degradation. Ni0.25Re0.75Se2 exhibited stability under varying pH, non-leaching behavior, and retained efficiency over cycles, showcasing potential for sustained use in industrial wastewater treatment. This research advances sustainable solutions to combat water pollution in urban and industrial environments.

An exhaustive exploration of Zn0.15Sn0.85(Se0.95S0.05)2 crystal-based photodetector and its potential application as a photocatalytic material

The research pioneers the exploration of synthesized quaternary Zn0.15Sn0.85(Se0.95S0.05)2 (ZSSS) crystals, demonstrating remarkable efficacy as optoelectronic switching devices and potent photocatalysts. The ZSSS photodetector recorded a stable photoresponse with remarkable rapid rise and decay times. The Langmuir-Hinshelwood kinetic model was used to look at the photocatalytic activity at different methylene blue concentrations. The researchers grew highly pure ZSSS crystals using the direct vapour transport (DVT) method. Field effect scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) images reveal the layer growth mechanism in the grown crystals. The structural analyses of the grown crystals were carried out using an X-ray diffraction (XRD) pattern and temperature-dependent Raman spectroscopy. The Lorentzian function was fitted to experimental data to carry out the temperature-dependent Raman analysis. The grown crystals exhibit a direct optical bandgap of 1.69 eV. The electrical analyses explain the semiconducting nature of the crystals.

Optimizing the performance of (Sb0.2Sn0.8)0.5(S0.9Se0.1)0.5 crystal-based self-powered photodetectors

The need to develop electronic systems capable of functioning without an external power source is an utmost priority, especially in the pursuit of self-powered photodetection. Through the direct vapor transport (DVT) method, we have synthesized a single crystal of the quaternary compound (Sb0.2Sn0.8)0.5(S0.9Se0.1)0.5 for self-driven photodetectors. The crystal's elemental composition was ascertained via energy-dispersive X-ray analysis (EDX), along with Field emission scanning electron microscopy (FESEM) provided insight into its surface morphology. The orthorhombic crystal system of the grown sample has been validated by a powder X-ray diffractometer (XRD). The regular spot pattern of SAED and the well-defined sharp peaks observed in the XRD graph collectively indicate the crystal's pronounced crystalline quality. The lattice parameters closely resemble the reported data. A UV–VIS-NIR spectrometer was utilized to deduce a direct optical band gap of 1.49 eV. Raman spectroscopy was used to examine different phonon modes. We analyzed its pulsed photo response by subjecting the grown crystal to different wavelengths and varying intensities of white light at self-biased mode and by applying 1 V bias. Our analysis enabled us to determine favourable photodetection parameters.

Influence of Antimony doping on electrical and photoelectrical response in Indium Selenide crystals

Indium Selenide (InSe) is the most suitable photovoltaic conversion material with narrow band gap (1.3 eV) in the layered semiconductors. The optical and transport properties of InSe offer significant potential for promising applications in the modern era of electronics and photo-electronic devices. The aim is achieved by high electric conductivity of InSe crystals, SbxIn1−xSe (x= 0.00, 0.10, 0.15, 0.20) crystals was grown by direct vapour transport (DVT) technique. The chemical compositional and surface morphology properties of grown crystals were studied by energy dispersive X-ray analysis (EDAX) and scanning electron microscope (SEM) respectively. The hexagonal crystal structure of grown crystal has revealed by X-ray diffraction (XRD) spectra. The dopant concentration of antimony (Sb) was found to have a decreasing effect on the optical band gap and activation energy as calculated through absorption spectra and Arrhenius relations respectively. The photo-response parameters: growth-decay and trap-depth parameters have been obtained using growth-decay curve. These results confirm that SbxIn1−xSe crystal was collective applicant for electronic and optoelectronic devices.

A comprehensive analysis of In0.15Sn0.85(Se0.95S0.05)2 crystals as a promising material for self-powered photodetector

The direct vapour transport technique was used to grow novel quaternary In0.15Sn0.85(Se0.95S0.05)2 crystals. Field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and energy dispersive X-ray analysis (EDX) with mapping were used to examine the surface morphology and chemical composition of grown crystals. The structural characterisation of grown crystals was analysed by X-ray diffraction (XRD), selected area electron diffraction (SAED), and Raman spectra. The grown crystals have a hexagonal crystalline structure, as confirmed by the structural characterisations. The direct optical bandgap of a grown crystal having 1.37 eV is obtained from absorption spectra. The current–voltage characteristics were studied within the temperature range of 108 K to 403 K. Also, the hall parameters have been obtained at room temperature. The thermodynamic and kinetic parameters were calculated from TGA, DTA, and DTG curves. The photodetector based on grown In0.15Sn0.85(Se0.95S0.05)2 quaternary crystal exhibits the outstanding self-powered photoresponse. The exhaustive photodetection properties of a photodetector based on a grown In0.15Sn0.85(Se0.95S0.05)2 crystal were examined as functions of various illumination intensities and wavelengths. Trap depth and photodetection parameters were also calculated.

Synthesis and characterization of peculiar (Sb0.2Sn0.8)0.5(Se0.9S0.1)0.5 crystal and its application as visible light photo-detector

To investigate the influence of Sb and S inclusion on SnSe characteristics, alloy engineering is carried out. The (Sb0.2Sn0.8)0.5(Se0.9S0.1)0.5 quaternary crystal was well synthesized via direct vapour transport (DVT) technique. The surface morphology, chemical composition, structural, optical, electrical, and photoconductive characteristics of the grown crystal were estimated using acceptable methodologies. The FE-SEM image revealed that the (Sb0.2Sn0.8)0.5(Se0.9S0.1)0.5 crystal has a flat surface, and the chemical composition was established using EDAX. X-ray diffraction (XRD) spectra further validated the orthorhombic structure of the crystal. Raman spectroscopy was employed to find different vibrational modes. The crystal exhibits a direct bandgap of 1.42 eV. The four-probe method and hot point probe method examination revealed the crystal to be an n-type semiconducting material. Additionally, an analysis of the pulsed photo response was carried out on the grown crystal, which was exposed to different wavelengths and white light at varying intensities, while subjected to a biasing voltage of 1 V, with an on/off period of 10 s. The results indicated that the device demonstrated rapid response to incident light, along with the presence of a trapping state, and favourable photodetection parameters, making it a viable material for a visible light photodetector.

Self-biased and biased photo-sensitivity of Tin Mono-Selenide (SnSe) photonic crystal Photodetector under poly/monochromatic light

Recently, transition metal chalcogenides were found to be the most promising candidates for photosensor- and photodetector-based applications. This study reports the photodetection and response properties of tin selenide (SnSe) crystals grown by the direct vapour transport (DVT) technique. The basic properties of SnSe have been reported in a previous article. Photodetection properties are investigated using polychromatic or monochromatic light of varying intensities and bias voltages. Results depict that detectors work congenially under monochromatic sources of light. It is observed that responsivity (Rλ) is higher for red, while detectivity and sensitivity are observed to be maximum for blue light under the self-biased (no bias) condition. The results observed under varying intensity (spot size) in the absence of biassing suggest that as intensity rises, all the parameters of the photodetector are also rising, while at constant intensity (30 mW/cm2), by varying the bias voltage, the detectivity of red light is decreasing due to an increment in dark current. Photodetectors are more efficient at converting optical signals to electrical signals, and their sensitivity is colour-dependent. Mainly, it is observed that monochromatic light shows high sensitivity to low bias voltages, while polychromatic light shows high sensitivity to high voltages. Observed results point to the detection of both monochromatic and polychromatic light by the fabricated detector, which can be applied to SnSe-based devices. A device can be used to fabricate colour and intensity detection.

Investigation of temperature‐dependent phonon dynamics of BixRe1−xSe2 (x = 0.0,0.1,0.5) via Raman spectroscopy

AbstractThe present study focuses on the growth and detailed investigation of temperature‐dependent phonon properties of BixRe1−xSe2 (x = 0.0,0.1,0.5) ternary alloys. Here, we have grown BixRe1−xSe2 (x = 0.0,0.1,0.5) ternary alloy crystals by the direct vapour transport (DVT) method and achieved high‐quality single crystals. The surface morphological validations of the crystals were determined by HRTEM analysis. The crystallinity of the samples was identified from the SAED pattern. The structural analysis was carried out with aid of powder X‐ray diffraction. The shift of the dominant peak towards higher 2θ shows the substitution of the Bi atom at Re sites. Further Raman spectra of the DVT‐grown crystals were recorded in the temperature range of 93 to 333 K. The temperature‐dependent Raman spectroscopy of the sample showed a steady redshift and peak broadening of Eg and two Ag peaks as the temperature varies from 93 to 333 K. Quantitative parameters such as peak position at 0 K (ω0) and first‐order temperature coefficient (χ) for Raman modes (Eg and two Ag) are calculated. The results were compared with theoretical models of the three‐ and four‐phonon processes and it was found that the three‐phonon process was responsible for the redshift in this case.

Investigations of SnS0.5Se0.5 ternary alloy crystals for their device application

Alloy engineered single crystals demonstrates enhanced electrical and optoelectronic properties. For this purpose, Crystals of tin sulfoselenide (SnS0.5Se0.5) have been synthesized by the Direct Vapour Transport (DVT) technique. The elemental, morphological, structural properties and high crystallinity of DVT grown SnS0.5Se0.5 crystals were investigated by EDAX, SEM, XRD and HRTEM respectively. The core-level spectra of SnS0.5Se0.5 crystals were studied by X-ray photoelectron spectroscopy (XPS). The electrical properties of grown crystals were studied by high temperature electrical resistivity measurement and Hall effect measurement. The electrical resistivity measurement was studied in different directions in the temperature range of 297 K–673 K. The SnS0.5Se0.5 ternary alloy crystal exhibits anisotropic performance and showed higher conduction in the in-plane direction. The study of temperature-dependent vibrational properties was carried out by Raman measurement experiment. The photodetection study was performed on a SnS0.5Se0.5 crystal-based device under different biasing voltages and intensities at an on/off period of 10 s and various photodetection parameters were also evaluated. The ternary alloyed crystal-based device exhibited good photoresponse and enhanced optoelectronic parameters.

High-performance self-biased photodetectors based on Bi-incorporated ReSe2 ternary alloys

Transition Metal Dichalcogenides (TMDCs) have recently been the focus because of their unique physical properties. Bi-incorporated ReSe2 (Bi: ReSe2) is a new member of the TMDC family with a triclinic structure that is optically biaxial and strongly anisotropic. In this work, we reported the effect of Bi doping in layered ReSe2 crystals synthesized by the Direct Vapour Transport (DVT) method and studied the structural and optoelectronic properties in detail. The layered surface of the single crystals, the stoichiometric proportion of elements and the triclinic structure and phase purity of the material has been observed using Scanning electron microscopy (SEM), Energy dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD) respectively. The shifting in vibrational Raman modes has been observed by Raman spectroscopy at room temperature. The dynamic I-t characteristics of BixRe1-xSe2 (x = 0.1, 0.5) ternary alloy-based photodetectors were studied successively. The photodetector parameters were calculated under different biasing voltages and different wavelengths. The anisotropy in the dynamic I-t characteristics of transition metal chalcogenides was studied due to their layered structure. The device showed higher photoresponse for the perpendicular to c-axis configuration than for the parallel. Our results showed that the ternary alloys based single crystals have great potential for application in photosensitive devices.

Synthesis and characterization of (Sb0.05In0.95)Se crystals

The antimony doped indium selenide (Sb0.05In0.95)Se crystals have been grown using the direct vapour transport (DVT) technique. The grown (Sb0.05In0.95)Se crystals have been characterized by estimating its structural, optical and electrical properties using appropriate techniques. The (Sb0.05In0.95)Se crystal has a hexagonal crystal structure with a preferred orientation along the (004) direction from the X-ray diffraction (XRD) spectra. Also, the micro-structural parameters (crystallite size, lattice strain, dislocation density, domain population) have been analysed from XRD spectra. The optical parameters (optical band gap, extinction coefficient and refractive index) have been calculated from UV–vis absorption spectrum. The resulting optical direct band gap is 1.51 eV. The activation energy value of 0.71 eV has been obtained from resistance-temperature observations of (Sb0.05In0.95)Se crystal.

A study of trap depth parameters and photo response parameters of tin diselenide (SnSe2) crystal

Tin diselenide (SnSe2) layered crystals have been grown by a direct vapor transport technique. SnSe2 is an anisotropic binary-layered material would see capable for highly potential applications. The stoichiometric proportion of constituent elements and structure of grown crystals have been accomplished by EDAX spectrum and powder X-ray diffraction analysis respectively. The X-ray diffraction practices of grown crystal revealed the type of structure and micro structural parameters of grown crystals. The Photo conducting responsivity (R*) = 21.7, 24.1, 24.9, 25.1 mA/W, specific detectivity (D) = 5.44 × 108, 6.05 × 108, 6.23 × 108, 6.30 × 108 jones and external quantum efficiency (EQE) = 4.087 %, 4.541 %, 4.678 %, 4.730 % are evaluated at illumination intensities 50 mW/cm2, 75 mW/cm2, 100 mW/cm2 and 125 mW/cm2 for photo-response characterization respectively. The trapdepth parameters of the SnSe2 crystals are explicated on the basis of defect controlled photoconductivity mechanism. The trap depth energies 550 meV, 551 meV, 542 meV and 538 meV are evaluated at illumination intensities 50 mW/cm2, 75 mW/cm2, 100 mW/cm2 and 125 mW/cm2 respectively. The investigational results confirm that the tin diselenide (SnSe2) layered crystals are accomplished for solar cell and photo-detection applications.

Self-powered photodetectors based on InxMo1-xS2 crystals

Transition metal dichalcogenides (TMDCs) have attracted global interest in recent years due to their optoelectronic characteristics and tunable bandgap energies. Due to their potential use in photovoltaic devices, photodetectors, and field effect transistor (FET) recording systems, single crystalline semiconductors of TMDC family have attracted a lot of attention. In the present article, the direct vapour transport technique was used to synthesis the InxMo1-xS2 (x = 0, 0.05, and 0.1) crystals. The purity and distribution of all the elements were investigated by EDAX mapping. The power X-ray diffraction technique examine the grown crystals have hexagonal lattice structure. The structure of all the crystals was investigated by scanning electron microscopy (SEM). The in-plane E2g and outer-plane A1g vibration modes were studied through Raman spectra. Photodetectors based on InxMo1-xS2(x = 0, 0.05, and 0.1) crystals show the self-powered photoresponse under white light source at 100 mW/cm2power intensity.

Thermal and electrical transport property study of direct vapour transport grown Cu2SnS3 single crystals

Copper tin sulphide (Cu2SnS3) (CTS) single crystals are grown by vapour transport technique of direct (DVT) type. The stoichiometric compositional analysis; Cu: 40.78 % (37.21 %), Sn: 31.09 % (34.35 %) and S: 28.13 % (28.15 %); showed the crystals to be slightly copper rich and tin deficient, bracket values are standard data. The X-ray diffraction showed the CTS to possess cubic unit structure having lattice parameter of 5.43 Å. The high resolution transmission electron microscopy substantiated the crystalline character. The thermal analysis are carried out by recording simultaneous thermogravimetric, differential thermogravimetric and differential thermal analysis curves. These analysis are done in inert atmosphere for three heating rates of 10, 15 and 20 K⋅min−1 in the range from ambient to 1023 K. The thermocurves are analyzed by two standard methods of Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The thermodynamic parameters like activation energy, changes of entropy, enthalphy and Gibbs free energy are determined using KAS and FWO methods. These determined thermodynamic parameters of as-grown CTS single crystals matches each other stating the validity of the analysis. Temperature variation of electrical transport properties like dc electrical resistivity (ρ) and Seebeck coefficient (S) are measured in the temperature range of 323 K to 473 K. The values of ‘ρ’ decreases with temperature, stating semiconducting nature of crystals. The observed ‘S’ values are found to be positive in entire temperature range, stating crystals to be of p-type semiconducting nature.

Synergistic effect of hafnium doping in tin diselenide for enhanced photodetection application

For long, photo-sensitive materials of transition metal dichalcogenides (TMDCs) have been explored in the semiconductor industry. TMDCs have superior environmental stability, apart from their strong light-matter interaction. Although Hafnium-based semiconductors capture great interest due to their high carrier mobility at room temperature, their optoelectronic applications are yet to be explored. Herein, we demonstrate the growth of large size HfxSn1-xSe2 (x = 0, 0.05, 0.1, 0.15, 0.2) single crystals by direct vapor transport (DVT) technique and optimized photodetection application. Grown crystals have a highly crystalline nature, attributing to the substitutional doping of Hf4+ on Sn4+-sites. With optimized stoichiometry and improved crystallinity, 5% Hf doped SnSe2 shows the superior photoresponse with the maximum photocurrent 198.28 μA under 120 mW/cm2 blue light intensity. The detector shows photoresponsivity of 16.52 mA/W and specific detectivity 19.44 × 109 Jones owing to the highest crystallite size for 5% HF doped SnSe2. This excellent result shows promising application of HfxSn1-xSe2 (x = 0, 0.05, 0.1, 0.15, 0.2) crystals as high-performance photodetector by improved crystalline nature.

Cryotronic Low‐Powered Strained Polymorphic Photodetector Functionalized by Palladium Incorporated Tin Diselenide

AbstractResearchers’ challenging task is to develop a material that can bear extreme environmental conditions. In this context, ‘metal dichalcogenide’ based solid‐state devices are highly beneficial for cryogenic optoelectronic applications but rarely reported. Herein, novel meta‐materials PdxSn1−xSe2 (x = 0.0, 0.2, 0.4) and their photodetector application are introduced. These ternary crystals are grown by direct vapour transport (DVT) technique in which palladium incorporated SnSe2 crystals exhibit polymorphism of hexagonal‐orthorhombic multiphase. PdxSn1−xSe2 (x = 0.0, 0.2, 0.4) single crystal photodetectors (SCPDs) demonstrate excellent photodetection in which SCPD functionalized by Pd0.4Sn0.6Se2 displays superior photoresponse. Cryogenic temperature directed blue‐shifting and sharpening of Raman peak displays noteworthy thermal‐sensing ability. Captivatingly, 10 µV low‐powered Pd0.4Sn0.6Se2 SCPD demonstrates substantial photodetection with 2.41 × 108 Jones detectivity at the cryogenic temperature of 10 K. To the best of the authors’ knowledge, a photosensor that displays excellent photodetection at a very low bias of 10 µV applied to the detector at the cryogenic temperature of 10 K is reported for the first time by them in present investigation. Higher stability, reproductiveness, and a low‐powered operating ability at a cryogenic temperature of 10 K declares Pd0.4Sn0.6Se2 as a potential candidate to design next‐generation low‐powered optoelectronic applications in cryotronics.

Self-powered anisotropic photo-responsive properties of tin mono-selenide (SnSe) photodetector

Transition metal chalcogenides (TMCs) have been extensively investigated due to their pervasive range of properties for the fabrication of several next-generation optoelectronic devices including flexible detectors, photodetectors, and photo sensors. This article reports the growth, characterization, and photodetection and response study of crystalline tin selenide (SnSe) grown by the direct vapor transport (DVT) technique. The stoichiometric confirmation of as-grown compound tin mono-selenide (SnSe) was confirmed by EDAX spectra. Structural confirmation was carried out using powder X-Ray Diffraction (PXRD). The bandgap of the grown crystals was also calculated from Tauc's plot. Anisotropic photodetection study of the SnSe photodetector demonstrates the superior photocurrent of 0.62 μA under polychromatic light for the I-II configurations of contacts. The stability of isotropic configuration is also observed to be high compared to anisotropic configuration. The results suggest isotropic contact configuration is most preferable for the SnSe photodetector. We observed that, under zero biasing conditions, the device performance improves, which indicates that the fabricated photo-diode exhibits an adequate photosensitive nature. It is observed that the device performs wisely under the self-driven condition, which points out the adequate photo-conductive (photo-self-driven) nature of the detector.

High-yield synthesis and investigations of bulk and exfoliated crystals of InxBi2-xSe3 (X = 0, 0.5, 1, 1.5, 2) ternary alloys

The synthesis of bulk ternary alloy compound of InxBi2-xSe3 (X = 0, 0.5, 1, 1.5, 2) have been done using Direct Vapor Transport (DVT) technique. High crystalline nanosheets were synthesized by Sonochemical exfoliation technique. The compositional, structural and optical properties of the synthesized InxBi2-xSe3 (X = 0, 0.5, 1, 1.5, 2) ternary alloy were investigated using relevant techniques. Chemical composition was confirmed by EDAX. The structural analysis was done using XRD (X-ray diffraction) and FE-SEM (Field emission scanning electron microscopy). Atomic Force Microscopy (AFM) and HR-TEM (high resolution transmission electron microscopy) shows the few layered liquid phase exfoliated nanosheets having good crystallinity. The crystallinity and layered growth mechanism of the material was observed. The adsorption coefficient was determined at the room temperature in the wavelength range 400nm-650nm.

ELECTRONIC TRANSPORT PROPERTIES (LOW TEMPERATURE HALL EFFECT MEASUREMENT) OF WSe2 SINGLE CRYSTAL

WSe2 crystals grown by Direct Vapour Transport (DVT) technique. The structural properties of as grown crystals have been measured by X-ray diffraction analysis. The temperature dependence Hall coefficient study revealed that the grown crystal shows mixed conduction behavior in the temperature region 300K to 10K. The variation of mobility with temperature, also show that the WSe2 possesses a mixed scattering mechanism. The Hall scattering factor calculated from the temperature dependent Hall coefficient and carrier density. Detailed analysis of temperature dependent Hall effect data thus yields information concerning the electronic transport properties of tungsten diselenide semiconducting layered materials.