ZnSe Thin Films Research Articles

Influence of Zinc Ion Concentration on the Structural, Surface Morphology and Optical Properties of Zinc Selenide Thin Films

ZnSe thin films were deposited on nonconducting glass substrates using different Zn[Formula: see text] ion concentrations. The films were deposited at 80[Formula: see text]C for 2.0[Formula: see text]h via photo-assisted chemical bath technique and annealed for 2.0[Formula: see text]h at 250[Formula: see text]C. X-ray diffraction revealed a hexagonal structure with preferred orientation along the (002) plane and the average crystallite size decreased from 10.5[Formula: see text]nm to 6.8[Formula: see text]nm with increased Zn[Formula: see text] ions. Raman spectra were used to confirm ZnSe phonon modes whose intensity increased with Zn[Formula: see text] ion concentrations although with fluctuation. Optical analysis showed higher absorbance and low transmittance in the visible region than near infrared making the thin films good materials for selective absorber surfaces. The band gap increased from 2.52[Formula: see text]eV to 2.78[Formula: see text]eV as the Zn[Formula: see text] ion concentration varied from 0.05% to 0.25%. The presence of the desired elements was confirmed by the EDS. Photoluminescence studies revealed three emission peaks which were all ascribed to defect state levels in ZnSe and all the samples emitted in reddish color according to CIE color chromaticity analysis. The selective absorption, wide band gap and broad emission properties suggest that the material is promising for optoelectronic applications.

Characterization of ZnSe Thin Film Electrodeposited at Room Temperature in Aqueous Medium without Complexing Agents

This study includes a simple electrodeposition technique for the fabrication of ZnSe thin film at room temperature and in an aqueous medium without additional complexing agents. Comprehensive analysis of the optical, structural, and morphological characteristics of the ZnSe thin film electrodeposited onto an ITO substrate was conducted using UV-Vis spectrometry, X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and field emission–scanning electron microscopy (FE–SEM). Furthermore, the photoelectrochemical properties were evaluated through current-time (I-t) measurements and electrochemical impedance spectroscopy (EIS) under light on/off conditions. Mott-Schottky analysis was also performed to determine the conductivity type, carrier concentration, and flat band potential of the ZnSe thin film. Structural investigations revealed that the ZnSe thin film has a hexagonal structure, the longitudinal optical (LO) phonon mode, stretching and bending vibration modes of Zn-Se. The carrier type of the ZnSe thin film was identified as n- type semiconductor and photoelectrochemical measurements exhibited a photoresponse under the light illumination

Fabrication of (ZnSe) thin films and study of their optical and structural characteristics

Fabrication of (ZnSe) thin films and study of their optical and structural characteristics

Theoretical DFT and experimental investigation of the effect of Co doping in electrochemically deposited ZnSe films

In this study, we examine the impact of introducing cobalt doping on the morphological, structural, optical, and electronic properties of ZnSe thin films produced by electrodeposition at room temperature. Characterization techniques, including X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and UV–Vis–NIR spectroscopy, were employed to analyze structural, morphological, and optical features. The developed films display a consistent and even distribution of grains with a cubic structure, showcasing a preferred orientation along the (111) axis. The calculated crystal size was estimated to be around 80 nm. The elemental composition of the film aligns with the synthesized deposition of elements. The introduction of cobalt resulted in enhanced optical properties and reduced energy bandgaps in the films. Concurrently, theoretical studies using the FP-LAPW approach in density functional theory were conducted, focusing on structural, electronic, and optical properties of cobalt-doped ZnSe at different concentrations (2 %, 4 %, 6 %). Theoretical findings demonstrated a substantial decrease in the bandgap, aligning well with the experimentally determined value of 2.72 eV. This coherence between theoretical predictions and experimental observations highlights the effectiveness of cobalt doping in influencing the optical characteristics of ZnSe thin films.

Comparative Assessment of Optical and Solid-State Characteristics in Antimony-Doped Chalcogenide Thin Films of ZnSe and PbSe to Boost Photovoltaic Performance in Solar Cells

Solar cell efficiency is crucial for maximizing the potential of solar energy as a sustainable power source. This research investigates the optical and solid-state properties of antimony-doped ZnSe and PbSe thin films using the spray pyrolysis technique. The process involves meticulous cleaning of soda-lime glass substrates, deposition of precursors (antimony chloride (SbCl3), lead chloride (PbCl2), hydrated zinc acetate (Zn (CH3COO) •3H2O), and sodium selenosulfide (NaSeSO3) via nebulizer-driven atomization onto heated substrates at a temperature of 80°C, and subsequent annealing at 300°C in a controlled nitrogen atmosphere for 60 minutes, facilitated by a tube furnace. Optical property evaluation through UV-Vis spectrophotometry reveals intriguing trends, such as a decrease in absorbance and an ascending transmittance with elongated wavelengths. Annealed films exhibit peak optical conductivity values around the visible spectrum, and augmented refractive indices correlate with increased wavelengths, further enhanced through annealing. Antimony doping influences band gap energy, making these materials promising for solar cell fabrication. This study underscores the potential of antimony-doped ZnSe and PbSe thin films to enhance solar cell efficiency. The films offer features like enhanced light trapping, lowered band gap energy, and improved charge transport characteristics, making them suitable for various solar cell applications, including antireflection coatings and light-trapping layers. Continued exploration and refinement of these materials are anticipated to lead to novel advancements in solar cell design and manufacturing, contributing to more efficient and impactful energy conversion techniques.

Review of novel approach and scalability forecast of ZnSe and Perovskite/Graphene based thin film materials for high performance solar cell applications

Abstract In the recent years, the using of fossil energy source-based fuels are delivering to the predetermined nature, health and environmental exposure, there is a universal necessitate prepared to well improvement and consumption of renewable energy source and apparatus. With the rapid growth of human life, energy is more essential. The explosive growth of population and energy consumption demands are the exclusive issue of the present world. In response to the energy demands, the growth of highly efficient energy conversion and storage devices. With increasing energy demands and environmental pollution, there is a requirement of the world to great some novel conducting materials consist of Perovskite solar cells (PSCs) which is delivered that excellent photoconversion efficiencies (PCE) compare with the other silicon supported photovoltaics, and also semiconducting materials for the conversion of substitute energy sources and preparation of high high-performance semiconductor devices. Semiconducting thin films play an indispensable role in fashionable science and electronic technology. Among them, the II–VI compound semiconductor thin films are an important class of materials, and they are generally comprehensive wide-band gap materials. In addition, the un-doped and rare-earth metal ions doped zinc selenide (ZnSe) thin films are currently the most demanding and technologically important materials, which have the potential for optoelectronic devices (solar cells, photoelectrochemical cell and light emitting diodes) and are active throughout the entire visible spectrum extending into the infrared wavelengths. Various techniques for depositing thin coatings on these substances are utilized to a greater extent. In this review, the most recent advanced techniques in the application of semiconducting materials-based thin films were produced in various energy-generated fields, particularly solar cells, with a major focus on a review of recent progress in the development of various types of ZnSe thin film-based material for high-performance semiconducting thin film material for solar cell application. Lastly, the advantages and material challenges of semiconductor-based thin films for future sanitary energy device process are described.

Effect of Cu ratios dopant on ZnSe thin films structural and optical properties

This study focused to prepare poly-crystalline (ZnSe)1-x Cux thin films, where x values vary from 0 to 0.1 %. the effect of Cu ratios dopant on structural, phases and optical properties has been investigated. As prepared thin films were deposited onto a cleaning glass substrate under high vacuum conditions (10-7 mbr) at room temperature using the “ evaporation technique”. The analysis results according to data of the X-ray diffraction technique of all films refer to the growth polycrystalline with hexagonal wurtzite structure of Zn-Se with no presence of any further phases. The changes in numerous parameters such as volume of the unit cell, atomic packing factor, dislocation density, lattice constant and bond length with the Cu ratio were estimated and described. As well, the crystallite sizes,D, the lattice micro-strain,ε and dislocation density,δ have been calculated the results evidence that the micro-structural parameters enhancement with increment Cu atoms. On the other hand, the optical parameters of the as-synthesized films (ZnSe)1-xCux (0 ≤ x ≤ 0.1) were performed utilizing “UV–V is spectro -photometer” with a wavelength range of 300 to 2400 nm. The results show that as the Cu ratio increases, the absorption edge shifts to a higher wavelength and the optical band gap, Eg opt decreases from 2.63 eV to 2.52 eV. Finally, the behaviour of the optical constant parameters as real,εr/ imaginary, εi parts, dissipation factor,tan δ, volume/surface energy loss functions and dispersion parameters were shown to depend on the variation of the Cu ratio and wavelengths.

An economic experimental approach to optimize the microstructure and thermoelectric performance of ZnSe thin films

An economic experimental approach to optimize the microstructure and thermoelectric performance of ZnSe thin films

Effects of terbium ions on the structural, morphological and optical properties of zinc selenide thin films prepared by photo-assisted chemical bath method

This study presents undoped and terbium doped ZnSe thin films deposited at different terbium III (Tb3+) ion concentrations using Photo-assisted chemical bath technique. The samples were characterized using glancing incidence X-ray diffraction (GIXRD), Raman spectroscopy, ultraviolet-visible spectroscopy, and photoluminescence (PL) spectroscopy, field emission scanning electron microscope, Atomic force microscopy and energy dispersive X-ray spectroscopy. The GIXRD and Raman peaks intensities, surface roughness and energy band gap increased with increasing Tb3+ ions concentration up to 0.8% and decreased thereafter. This behavior, which is equally observed in the PL emission, is ascribed to concentration quenching due to the presence of natural defect in the host material. Three PL emission peaks all associated with the defects were observed at 535, 672 and 743 nm. The thin films morphology transformed from flakes to spherical grains with increased Tb3+ ions concentration and the presence of the expected elements was confirmed. The deposited films have potential applications in light emitting devices.

Analysis of surface properties of Mg doped ZnS and ZnSe thin films through x-ray photoelectron spectroscopy

The surface properties of the spray-deposited Mg-doped ZnS and ZnSe films were investigated using X-ray photoelectron spectroscopy (XPS). The energy levels of the core electrons in ZnMgS and ZnMgSe, their peak positions, area ratios, and full width at half maximum were determined. Chemical shifts in Auger peaks, which are highly sensitive to changes in the chemical environment were used in the analysis. Compositional analysis indicated selenium deficiency in the ZnMgSe films. XPS peak of magnesium 2p showed a shift from 50.46 eV for ZnMgSe film to 50.63 eV for ZnMgS film and Mg 2s peak shift from 86.56 eV for ZnMgSe to 87.64 eV for ZnMgS films. A careful justification for the formation of oxides in the ZnMgSe films is also given. Ionicity for both films is about 0.51. Peak shifts in the Auger and core-level peaks are used to analyze the material's bonding strength, oxidation states, and bonding types.

Multi-wavelength passively Q-switched laser with Co2+:ZnSe thin film coated microsphere

We experimentally demonstrate an all-fiber passively Q-switched erbium-doped laser based on a microsphere resonator coated with Co2+:ZnSe film, which can achieve multi-wavelength pulse laser. With electron beam evaporation technology, the saturable absorber (SA) with a modulation depth of 55% was prepared by depositing Co2+:ZnSe film on the microsphere for the loss modulation of the laser cavity. The passively Q-switched output pulses were obtained by inserting the SA into the laser cavity and the narrowest pulse width of ∼3 μs was obtained. The fiber laser can stably output quintuple-wavelength laser pulses with a 3 dB bandwidth of ∼0.1 nm. The wavelength interval of multi-wavelengths was stably maintained at ∼1 nm and the smallest optical signal-to-noise ratio of ∼10 dB at the pump power of 400 mW was measured. The signal-to-noise ratio was ∼58 dB, which confirms excellent output stability. The results prove that it is a promising SA device to achieve passively Q-switched multi-wavelength pulse fiber lasers.

Achieving phase stability in ZnSe thin films by thickness and annealing recipes for optical window applications

Achieving phase stability in ZnSe thin films by thickness and annealing recipes for optical window applications

Study of Optical and Electrical Properties of RF-Sputtered ZnSe/ZnTe Heterojunctions for Sensing Applications

Cadmium (Cd)-free photodiodes based on n-type Zinc Selenide/p-type Zinc Telluride (n-ZnSe/p-ZnTe) heterojunctions were prepared by Radio Frequency-Magnetron Sputtering (RF-MS) technique, and their detailed optical and electrical characterization was performed. Onto an optical glass substrate, 100 nm gold (Au) thin film was deposited by Thermal Vacuum Evaporation (TVE) representing the back-contact, followed by the successive RF-MS deposition of ZnTe, ZnSe, Zinc Oxide (ZnO) and Indium Tin Oxide (ITO) thin films, finally resulting in the Au/ZnTe/ZnSe/ZnO/ITO sub-micrometric “substrate”-type configuration. Next, the optical characterization by Ultraviolet-Visible (UV-VIS) spectroscopy was performed on the component thin films, and their optical band gap values were determined. The electrical measurements in the dark and under illumination at different light intensities were subsequently performed. The Current–Voltage (I–V) characteristics in the dark are nonlinear with a relatively high asymmetry, following the modified Shockley–Read equation. From their analysis, the series resistance, shunt resistance, the ideality factor and saturation current were determined with high accuracy. It is worth noting that the action spectrum of the structure is shifted to short wavelengths. A sensibility test for the 420–500 nm range was performed while changing the intensity of the incident light from 100 mW/cm2 down to 10 mW/cm2 and measuring the photocurrent. The obtained results provided sufficient information to consider the present sub-micrometric photodiodes based on n-ZnSe/p-ZnTe heterojunctions to be more suitable for the UV domain, demonstrating their potential for integration within UV photodetectors relying on environmentally-friendly materials.

Fabrication and characterization of ZnS and ZnSe absorber layers for UV-selective transparent photovoltaics

We have fabricated ZnS, ZnSe and mixed Zn(S,Se) thin film layers for application as solar cell absorbers in ultraviolet (UV)-selective solar cells. We fabricated the thin film layers using a two-step process involving evaporation of the Zn layer followed by an anneal in an H2S and/or H2Se containing atmosphere. A study of the annealing conditions was performed to minimize hole formation in the thin film layer. A mixed Sulfur and Selenium containing layer was also developed in order to reach a 3 eV band gap, such that the layer absorbs all the UV light and leaves the visible light passing through. Next, we tried to increase the conductivity of the layer by adding extrinsic doping elements. Cu was found to increase the conductivity by more than three orders of magnitude, while leaving the transparency of the layer mostly unchanged. Finally, solar cell devices were fabricated using transparent back and front contacts and a NiO buffer layer. We could measure a very small photocurrent of about 100 μA/cm2 and an open circuit voltage of about 500 mV under AM1.5 G illumination.

A Two-step Method to Grow ZnSe Thin Films and To Study their Characteristics

A Two-step Method to Grow ZnSe Thin Films and To Study their Characteristics

Investigation of porous ZnSe thin films prepared by thermal evaporation

ZnSe films with thickness of 50, 70 and 100 nm were prepared on Corning 7059 glass substrates at room temperature by applying continuous or periodically interrupted physical vapour deposition at very low deposition rates (0.2 and 0.5 nm s−1). Part of the films was annealed at 200 °C after deposition. Optical absorption spectra determined from spectroscopic ellipsometry data show direct allowed transitions, which indicate that the films have microcrystalline structure. This is in agreement with scanning electron microscopy and atomic force microscopy results. The spectroscopic ellipsometry results also show that the porosity of the films is strongly affected by both manner of deposition and deposition rate; the annealing causes some porosity decrease. Optical transmission spectra reveal that the transmittance of as-deposited films, obtained by periodically interrupted manner is significantly influenced by their porosity.

Study of the structural, morphological and optical properties of ZnSe doped with Yb3+

A wurtzite phase of Zn 1−x Yb x Se (0 ≤ x ≤ 1.8) nanoparticles was synthesized through photo assisted chemical bath deposition. Glancing angle X-ray diffraction disclosed a hexagonal wurtzite crystal structure. The crystallite size (D) of undoped ZnSe was estimated 24.40 nm and then gradually decreased to 4.66 nm, after Yb 3+ doping. Scanning electron microscopy images revealed that with an increase in the Yb 3+ concentration, the thin film morphology transformed from Nano-flakes to spherical particles. The expected elements were confirmed by elemental energy X-ray dispersive analysis. Raman spectroscopy revealed the existence of two distinct optical phonon peaks induced by first- and second-order longitudinal vibration peak located at 257 and 500 cm -1 , respectively. UV–visible spectroscopy elucidated that the absorption spectra showed that the band gap energy for undoped ZnSe thin films can be tuned in the range of 2.76 - 3.12 by varying Yb 3+ concentration. Photoluminescence analysis revealed two emission and shoulder peaks located at 3.19 eV, 2.37 eV and 1.70 eV, which were ascribed to the band-to-band and imperfections of ZnSe, respectively. Chromaticity investigations revealed that the blue emission color was dependent on the concentration of Yb 3+ . The results suggest that Zn 1−x Yb x Se (0 ≤ x ≤ 1.8) is a promising candidate for blue-light emitting phosphor. The data that support the findings of this study are available from the corresponding author upon reasonable request.

Physical characterization of Ge–Zn–Se thin films

Physical characterization of Ge–Zn–Se thin films

Wavelength dependence of nonlinear optical susceptibility of ZnSe nanocrystalline film

The present work reports the nonlinear optical susceptibility of nanocrystalline ZnSe thin films with different thicknesses, measured using third-order harmonic technology at irradiation wavelengths λ of 1200–1900 nm. The results show that the third-order nonlinear susceptibility χ(3) of ZnSe thin films is a function of the pump wavelength and film thickness. The χ(3) values for the thinner 202-nm film generally decreased with the redshift of the wavelength and were approximately 10−20 m2/V2 at λ ≤ 1500 nm and 10−21 m2/V2 at λ > 1500 nm. The χ(3) values for the thicker 1021-nm film did not follow a decreasing trend, but instead exhibited local peaks at 1350, 1500 and 1750 nm, with a maximum value of approximately 2.4 × 10−19 m2/V2 at λ = 1750 nm. Within 1200–1900 nm, the χ(3) of the thicker film was always greater than that of the thinner film. In addition, a weak second-order harmonic at wavelengths within 1100–1300 nm was observed for the 1021 nm ZnSe thin film. The large difference in the nonlinear optical properties between the thinner and thicker film samples is conjectured to be caused by the increased density of geometric defects and the gradual formation of local anisotropy with increasing film thickness. Nonlinear optical coefficient measurements of ZnSe thin films with different thicknesses over a broad spectrum are important for the application of these films in nonlinear thin-film optoelectronic devices.

Effects of SeO2 epilayer on the structural, morphological, optical and dielectric properties of nanocrystalline ZnSe thin films

Herein the effects of SeO2 coating on the physical properties of thermally evaporated nanocrystalline (NC) ZnSe thin film substrates are explored. The formed ZnSe films showed nanocrystalline Zincblende phase. They contained excess selenium (ZnSe1.07) with relatively large defect density and displayed band gap of value of 3.48 eV, energy band tails of width of 1.2 eV and dielectric quality factor (Q) less than 100. Coating NC-ZnSe with SeO2 induced the crystallization of tetragonal SeO2 and enhanced the light absorbability of SeO2. It also reduced the defect density and stacking faults, increased the crystallites sizes, narrowed the width of band tails, increased the dielectric constant and increase the Q factor up to ∼400 of NC-ZnSe. In addition, analysis of the optical conductivity spectra for the NC-ZnSe/SeO2 bilayers has shown that the drift mobility, plasmon frequency and free carrier density can reach values of 30.42 cm2/Vs, 5.07 GHz and 8.0 ×1018 cm−3, respectively.