No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Surface Deformation of Cadmium Selenide Thin Films By DEHI Technique
Abstract
Here, the Double Exposure Holographic Interferometry (DEHI) technique is used to study the surface deformation of CdSe films electrodeposited on stainless steel substrate. The electrodeposition of CdSe thin films is carried out by varying the time of deposition. The deposition potential of the compound was studied by cyclic voltammetry. The structural, surface morphological and optical properties of the deposited films have been studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and optical absorption technique respectively. Also the contact angle measurements are carried out. The DEHI technique is used to determine, thickness of thin films, mass deposited, fringe width and stress to substrate of electrodeposited CdSe thin films for various deposition time with different solution concentrations. With increasing deposition time fringe width was decreased due to the reduction in film stress
... Moreover, deviation from stoichiometry does not always have a negative effect, but can have a positive effect on the photocatalytic properties or structural transformations [15][16][17][18][19][20]. Among the huge number of methods for producing thin films based on CdSe, we can distinguish the method of electrochemical or galvanic synthesis, which allows not only to control the thickness of the obtained films, their isotropy and uniformity of production, but also by varying the applied potential differences to vary the stoichiometry of the resulting structures [21][22][23][24][25]. The variation in stoichiometry is due to different potentials for the reduction of ions from an electrolyte solution, which leads to different rates of crystalline structure formation with a predominance of one or another component. ...
... The variation in stoichiometry is due to different potentials for the reduction of ions from an electrolyte solution, which leads to different rates of crystalline structure formation with a predominance of one or another component. Despite a large number of scientific studies in this area, the topic of studying the effect of stoichiometry on the properties of thin CdSe films, as well as the expansion of their practical application, has not weakened so far [22][23][24][25][26][27][28][29]. ...
The interest in thin films based on chalcogenides, among which CdSe structures stand out, is due to the great prospects for their use as various photocatalysts, microelectronic devices, etc. However, despite the large number of scientific works in the field of studying the properties of semiconductor thin films, there are still many unresolved issues. In this regard, the main goal of this work is a systematic study of the influence of electrochemical deposition conditions, in particular, in the applied potential difference, on the change in the structural and optical properties of CdSe-based thin films, as well as assessing the applicability of the obtained thin films in photocatalytic decomposition reactions of tetracycline hydrochloride. Atomic force microscopy, X-ray diffraction, energy-dispersive analysis, and UV spectroscopy were used as research methods. In the course of the study, the dependences of the change in the stoichiometry of thin films on the applied potentials difference were established, in particular, it was found that an increase in the potential difference of more than 1.5 V leads to an increase in cadmium in the structure of the films. By the method of X-ray diffraction it was found that for thin films obtained with an applied potentials difference in of 1.75–2.0 V, in addition to the main hexagonal phase of CdSe, the appearance of weak diffraction reflections characteristic of the hexagonal phase of cadmium is observed. The prospects of using synthesized thin films as photocatalysts, which showed good photocatalytic activity over time, which ranged from 50 to 70%, are shown. In this case, films with a nonstoichiometric ratio of elements have the highest photocatalytic activity.
Here, cadmium sulfide (CdS) thin films have been prepared by electrodeposition method using aqueous basic electrolyte. The electrodeposition of CdS thin films has been carried out by varying the concentrations. The deposition potential of the compound was studied by cyclic voltammetry. The as-deposited and irradiated CdS thin films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and optical absorption technique for different bath concentration. The XRD shows multi crystalline phases having (1 1 0) major peak. The band gap was found to be 2.3 and 2.4 eV was as deposited and irradiated flim. The layers were subjected to irradiation with 6 MeV electrons.
Одними из перспективных материалов на сегодняшний день в области полупроводников являются структуры на основе кадмия, селена, теллура и их соединений, имеющих один структурный тип AIIBVI, интерес к которым обусловлен возможностью их применения в различных фотоэлектронных устройствах, солнечных элементах, светодиодах, катализаторах и т.д. Данная работа посвящена изучению свойств тонких пленок на основе CoCdSe. В качестве метода синтеза использовался метод электрохимического осаждения, который позволяет с высокой точностью получать тонкие пленки с заданными параметрами. Получены результаты влияния разности прикладываемых потенциалов на структурные особенности CoCdSe тонких пленок. В качестве подложек для получения тонких пленок использовались полимерные пленки полиэтилентерефталата, обладающие хорошими адгезионными свойствами, позволяющими получать равномерные по высоте и составу тонкие пленки. Установлено, что изменение разности прикладываемых потенциалов приводит не только к изменению толщины тонких пленок при заданном временном интервале синтеза, но и изменять стехиометрический и фазовый состав тонких пленок. С применением метода рентгенофазового состава установлено, что увеличение разности прикладываемых потенциалов приводит к увеличению фазы CoSe, а также структурным упорядочениям и снижению дислокационной плотности дефектов в пленках.
The paper presents the results of a study of the effect of the applied potentials difference on the properties of thin films based on CoCdSe. It is shown that the use of the galvanic deposition method allows not only controlling the thickness of the synthesized films by changing the applied potentials difference, but also changing the stoichiometric and phase composition of thin films. It was found that an increase in the applied potentials difference leads to the domination of the CoSe phase in the structure of thin films, leading to structural ordering and a decrease in the dislocation density of defects and an increase in the density of thin films. It was found that the formation of the CoSe phase in the structure of thin films and its subsequent increase leads to a shift in the band gap from 3.5 eV to 3.8 eV. The change in the band gap is caused by a change in the phase composition, as well as stoichiometry of thin films, with a predominance of cadmium in the structure. The prospects of using thin films based on CoCdSe as the basis for photocatalytic reactions are shown.
Thin films of CdSe were deposited by potentiostatic mode on different substrates such as stainless steel, titanium and fluorine
tin-oxide (FTO) coated glass using non-aqueous bath. The preparative parameters were optimized to get good quality CdSe thin
films. These films were characterized by X-ray diffraction (XRD), optical absorption and photoelectrochemical (PEC) techniques.
XRD study revealed that the films were polycrystalline in nature with hexagonal phase. Optical absorption study showed that
CdSe films were of direct band gap type semiconductor with a band gap energy of 1·8 eV. PEC study revealed that CdSe film
deposited on FTO coated glass exhibited maximum values of fill factor (FF) and efficiency (η) as compared to the films deposited on stainless steel and titanium substrate.
Thin films of Cd-Fe-Se have been prepared onto stainless steel substrates, for various compositions of Cd and Fe and solution concentrations by an electrodeposition technique. Cd0.9Fe0.1Se films, electrodeposited with a solution concentration of 10 mM, forming a photoelectrochemical (PEC) cell using ferri-ferrocyanide electrolyte, show a better PEC performance. The films deposited using optimized composition (9:1:10), solution concentration (10 mM), deposition time (30 min) and current density (1 mA/cm2) have been used for further characterization by X-ray diffraction (XRD) and PEC techniques. It has been found that the as-grown films are polycrystalline in nature with orientations along the peaks of hexagonal CdSe and FeSe. It has also been found from the current-voltage and power output characteristics that n-Cd-Fe-Se/ferri-ferrocyanide junctions show good rectifying nature and the efficiency of the n-Cd0.9Fe0.1Se/ferri-ferrocyanide/C PEC cell is 0.41% with FF≈50%.
We have studied the influence of annealing temperatures on the crystal structure, surface morphology, optical and photoelectrochemical (PEC) properties of CdSe nanofiber film electrodes synthesized by electrodeposition technique. The crystal structure and surface morphology of CdSe film electrodes were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, respectively. The optical absorption study of as-synthesized and annealed CdSe films on tin-doped indium oxide (ITO) substrates were measured by spectrophotometer. As-synthesized amorphous/nanocrystalline CdSe film electrodes were changed to crystalline after annealing at 473K for 1h, where the improved photoelectrochemical performance conversion efficiency of 2.01% was obtained.
CdSe and Cd(Se, Te) alloy layers were electroplated onto titanium substrates from both acid and alkaline baths. When annealed, these layers show good photoelectrode behaviour in a polysulphide electrolyte with high quantum efficiencies and stability. Donor densities are found to be in the range of 1014–1015 cm-3. Scanning electron microscopy studies show the layers to have a very irregular morphology and generally to be composed of elongated spherical particles. Annealing conditions can be chosen such that the layers are of cubic or hexagonal structure.
Polycrystalline CdX (X=S, Se, Te) films are electrodeposited from aqueous and non-aqueous (ethylene glycol) baths onto different substrates at different temperatures. In order to increase the conductivity of the films, as-deposited films are annealed in a nitrogen atmosphere. Photoelectrochemical studies are carried out using 1M NaOH–1M Na2S–1M S electrolyte under light intensity of 37mW/cm2. From photoelectrochemical characterisations it is concluded that the deposited CdS, CdSe and CdTe are n-type semiconductors. Interestingly the CdX films deposited from aqueous and non-aqueous baths showed comparable photoelectrochemical properties.
Double-exposure holographic interferometry (DEHI) technique was used to study the surface deformation of stainless steel substrate, when cobalt oxide was deposited onto it using dc electrodeposition method. The films were deposited by varying the concentrations of CoCl2 solution and the deposition time. It was observed that interference fringes were localized on the surface of substrate when the hologram was transilluminated. It was further noticed that the fringe spacing changes with solution concentration as well as time of deposition. The thickness of deposited film, mass of cobalt oxide deposited on the substrate and rate of mass deposition were evaluated.
In this paper, we present the characterization of cadmium selenide thin films by electrodeposition method. We employ various
depositions times for different concentrations of solutions. The structural, optical, surface morphological and surface wettability
properties of the deposited films have been studied by X-ray diffraction (XRD), optical absorption, scanning electron microscope
(SEM) and contact angle measurement respectively. We report a technique, which uses double exposure holographic interferometry
(DEHI) technique together with simple mathematical interpretation which immediately locate thickness of thin films, mass deposited,
stress to substrate and fringe width for various depositions times with different concentrations of solutions.
KeywordsDEHI–Thin films–Electrodeposition–CdSe–XRD–SEM
The properties of thin films depend to a large extent upon their mechanical stability which in turn is dependent on the intrinsic stresses developed during evaporation. This paper describes a simple method for the measurement of stresses in thin films by the use of real-time holographic interferometry.
We describe the latest improvements in holographic interferometry that enable the real-time measurement of vibrational modes and static deformations in surfaces using low-power laser illumination and a photorefractive Bi12TiO20 crystal as the recording medium. An efficient setup has been developed where the most critical elements have been optimized: target illumination and backscattered light collection, distribution of light between the object and reference beams, and stabilization system operation. Experimental results for vibration and deformatiom measurement are reported.
The chemical bath deposition of CdSe layers has been studied by means of quartz crystal microbalance (QCM) experiments, combined with TEM, HREM observations and EXAFS measurements. From mass vs time measurements and the modelling of the time derivative, it is established that the nucleation/growth process occurs via two steps : the first one corresponds to an instantaneous nucleation of cylindrical nuclei, with a 2D-growth until a complete coverage of the substrate ; the second one consists of a 3D-instantaneous nucleation and growth process occuring on sites randomly distributed on the evolving surface. The addition of silicotungstic acid to the deposition bath is shown to influence the growth kinetics of the CdSe deposit. Nanocrystalline deposits with the cubic blende structure are obtained showing confinement effects. After thermal treatment CdSe shows an hexagonal wurtzite structure with a large density of defects and the grain size is increased.
Studies on photoelectrochemical storage cells formed with chemically deposited CdSe and Ag2S electrodes, solar Energy materials and solar cells
- S S Dhumure
- C D Loknande
Surface deformation of BaSrTiO3 by DEHI technique
- Gangawane