Effect of substrate temperature on structural and morphological parameters of ZnTe thin films

Vacuum evaporated thin films of Zinc Telluride (ZnTe) of 5000 Å thickness have been deposited on glass substrates at different substrate temperatures (303 K, 373 K, 448 K). Structural parameters were obtained using XRD analysis. Atomic Force Microscope (AFM) in non-contact mode has been used to study the surface morphological properties of the deposited thin films. The results obtained from structural and surface morphological studies have been correlated and it is found that the films deposited at higher substrate temperatures possess increasingly good crystallinity and smoother surfaces. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/930

Temperature dependent I-V characteristics of Ag/p-Sn0.2Se0.8 thin film Schottky barrier diode

Ag/p-Sn0.2Se0.8 Schottky barrier diodes have been fabricated and characterized by the current-voltage (I-V) technique as a function of temperature in the range of 303 K to 403 K. The forward bias characteristics have been analyzed on the basis of thermionic emission (TE) theory and the characteristic parameters of Schottky barrier diode such as barrier height, ideality factor and series resistance have been determined. The conventional Richardson plot was drawn and the value of Richardson constant was determined using the intersection of Ln(I0/T2) vs 1000/T. It is found to be around 15 Acm – 2K – 2 which is closer to the reported value for SnSe. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2212

Synthesis and Photodetection Properties of Sonochemically Exfoliated Cu0.2Sn0.8Se Nanoparticles

Transition metal chalcogenides (TMCs) with atomically minute structure have shown excessive potential for their optoelectronics field applications and their counterparts. TMCs unique layer dependent properties have pinched increasing consideration of scientists. Here, the high yield synthesis of atomically minute Cu0.2Sn0.8Se nanoparticles has been reported. The nanoparticles are synthesised by sonochemical exfoliation technique. The exfoliated Cu0.2Sn0.8Se nanoparticles have orthorhombic lattice structure which is confirmed from powder X-ray Diffraction with Pnma space group. The lateral morphology of the assynthesized nanoparticles examined under transmission electron microscopy showed them to be of uniform spherical shape. The selected area electron diffraction showed a spot pattern stating the particles to be single crystalline. Moreover, the photodetector based on Cu0.2Sn0.8Se nanoparticles thin film is fabricated. The periodic 670 nm laser illumination of power intensity 3 mW/cm2 is used to study the detector properties. The enhanced photo responsivity and specific detectivity is observed along with fast response. The outstanding detection properties are revealed from the responsivity, specific detectivity, and external quantum efficiency (EQE) of Cu0.2Sn0.8Se nanoparticles-based photodetector

X-ray diffraction analysis of orthorhombic SnSe nanoparticles by Williamson–Hall, Halder–Wagner and Size–Strain plot methods

SnSe nanoparticles were synthesized using the sonochemical exfoliation technique, employing SnSe single crystals. Various analysis, including Energy Dispersive Analysis of X-rays-Elemental mapping, X-ray Diffraction (XRD), High-Resolution Transmission Electron Microscopy, Ultra-Violet Diffused Reflectance Spectroscopy-Photoluminescence measurements, Raman spectroscopy, and X-ray Photoelectron Spectroscopy, were conducted to determine the chemical composition, crystalline phase, morphological characteristics, optical properties, vibrational modes, and oxidation states of the synthesized nanoparticles. The XRD peak broadening analysis, specifically employing Williamson–Hall (W-H), Size–Strain Plot (SSP), and Halder–Wagner Method (H-W), was employed to examine particle size and intrinsic strain. Additionally, three models within the W-H method, namely the uniform deformation model (UDM), uniform stress deformation model (USDM), and uniform deformation energy density model (UDEDM), were used to investigate physical and microstructural parameters such as strain, stress, and energy density. A comprehensive comparison of the average particle size results obtained from Williamson–Hall, Size–Strain, and Halder–Wagner Methods, along with results from HR-TEM and Particle Size Analysis, was carried out. The comprehensive comparison of results from different techniques adds credibility to the reported findings

Growth and application of WSe

Tungsten di-selenide (WSe2) belonging to the family of layered transition metal di-chalcogenides (TMDCs) is at present widely used in optoelectronic devices due to their adequate energy band gap suitable for photosensing applications. In the present investigation, WSe2 single crystals are grown by direct vapor transport (DVT) technique in a dual zone horizontal furnace maintaining a temperature difference of 50 K between source zone (SZ) and growth zone (GZ). The crystals thus obtained were thin, shiny and with an average thickness of 30 mm. The surface topography of crystals studied by optical microscope revealed hexagonal spirals on the crystal surface which seemed to arise due to screw dislocation defect. The structural properties of the as grown crystals studied by powder X-ray diffraction (XRD) elucidated good crystallinity, hexagonal structure and confirmed the orientation of crystals along crystallographic c-axis. P-type semiconductor nature of the crystals was affirmed by thermoelectric power (TEP) measurement. Optical and vibrational properties of the grown crystals were studied by UV–Visible, photoluminescence (PL) and Raman spectroscopy. An optical direct band gap of 1.41 eV was determined for the crystals which were micromechanically exfoliated upto few layers. The excitonic mechanism of the grown WSe2 crystal was explained by PL spectroscopy. The results of Raman spectroscopy disclosed A1g and E2g vibrational modes present in the crystals. The current–voltage characteristics of nSnSe/pWSe2 hetero-structure studied using Keithley 2400 SMU showed rectification behavior at low bias voltage in dark and illuminated conditions. The diode parameters like ideality factor and barrier potential were determined to be 2.54 and 0.4 eV, respectively, by following conventional lnI–V method. The photodetection properties of the fabricated device were studied using a Laser source (670 nm) having an intensity of 3 mWcm−2at different bias voltage ranging from 0.3 V to 3 V. Parameters such as responsivity, detectivity and external quantum efficiency (EQE) were calculated to substantiate the excellent detection properties shown by the prepared photodetector using time resolved pulsed photoresponse. Value of responsivity and EQE increased from 42.22 mA W−1 to 533.77 mA W−1 and 7% to 95%, respectively, with increase in bias voltage from 0.3 V to 3 V. Also, detectivity values were found to be of the order of 107 Jones