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Semiconducting materials are pivotal in various fields, such as solar cells, LEDs, photovoltaic cells, etc. A nature‐friendly chitosan is a good film‐forming, water‐soluble polymer that is modified to a small band‐gap polymer for various optoelectronic applications. Choline chloride:ethylene glycol:glycerin (1:1:1) deep eutectic solvent (DES)‐modified activated carbon is incorporated into the chitosan matric and this composite is fabricated into thin films via spin coating methodology. The obtained films are subjected to multiple studies such as scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), impedance spectroscopy, and UV–vis spectroscopy to perceive the thin‐films microstructure, morphology, conductance, band gap, and optical nature. The integration of DES‐modified activated carbon has significantly improved the charge transfer capacity of chitosan by reducing the band gap from 4.0 to 2.0 eV. These notable characteristics exhibited by the modified films can be key to sustainable semiconducting materials and have the potential to transform several optoelectronic applications. [ABSTRACT FROM AUTHOR]

In this study, nebulizer spray pyrolysis was used to develop Bi2S3 thin films at various coating temperatures (250 to 375 °C) for photodetector application. Studies on the Bi2S3 thin film's structural, morphological, and optical effects upon coating temperature were conducted. The Bi2S3 thin films feature an orthorhombic structure, with the increase in crystallite size as the coating temperature increases at 350 °C. Using FESEM measurement, the morphology of the thin film surface has uneven grain shape and size distribution which improves upon high coating temperature. The increment in optical absorbance and decrement in bandgap was observed with the increase in coating temperature through UV–Vis. spectroscopy. According to photoluminescence spectroscopy, the excitonic recombination and existence of defects related to Bi and S ions in the host material caused the origin of luminescence peaks. Finally, the calculated optical sensing metrics, including responsivity (R), detectivity (D*), external quantum efficiency (EQE), and response/ decay times were found to be 1.58 × 10−1A/W, 9.75 × 109Jones, 50.8%, and 0.3/0.4 s, respectively for the Bi2S3 film coated at 350◦C based photodetector. The results of this study suggest that the bismuth sulfide thin film photodetector coated at 350 °C could be optimal for use in commercial optoelectronic applications. [ABSTRACT FROM AUTHOR]

In recent years, compounds from the chalcogenide family have gained importance in thin film technology due to their potential applications in photovoltaic cells, X-ray and gamma-ray detectors. CdZnTe is a II-VI compound semiconductor and is used in photovoltaic solar cells due to its high efficiency and tunable band gap. CdZnTe thin films have properties intermediate between those of CdTe and ZnTe. Their addition creates a common lattice in which the energy band gap is larger than that of ZnTe, making the material more attractive for electronic device fabrication. In this work, CdZnTe films (X = 0.1M, X= 0.2M, and X=0.5M) were deposited on a nickel substrate by chemical bath deposition in a non-aqueous medium. The growth parameters of the CdZnTe film can be adjusted by varying the concentration (X=0.1M, X=0.2M, and X=0.5M) of the Zn content. The varying Zn content regulates the growth rate of CdTe and is an important factor affecting the properties of the film. The chemical bath deposition method was used to vary the different Zn concentrations in the range of 0.1M, 0.2M, and 0.5M, and their effects on various properties of the CdZnTe films were investigated. The effects of Zn doping on the structural, morphological, elemental, and optical properties were studied by XRD, SEM, EDS, FTIR, UV-Visible, and PL. The X-ray diffraction study showed that all films have a cubic zinc-blende structure with a (111) plane. The crystallite size was calculated using the Scherrer formula, and it was found that the crystallite size decreases with increasing Zn content. [ABSTRACT FROM AUTHOR]

Zinc Cadmium Sulphide (ZnCdS) is a ternary direct band gap semiconducting material having potential applications in different opto-electronic devices. The deposition temperature can be effectively used to enhance the structure and optical properties of the films. In this paper, we have investigated the effect of air annealing on the various properties of ZnCdS films. A nanocrystalline ZnCdS thin film was successfully deposited on molybdenum substrate and the effect of annealing on structural, morphological, and optical properties were studied. The main impact was found to be slightly increase in crystallite size which effectively reduced the defects. It is observed that deposited film annealed at higher temperature provide a smooth and flat texture suited for optoelectronic applications. SEM photographs reveals the deposited grains are well connected and uniformly distributed over the surface. The experimental results show that the energy gap of the films is not much affected by the annealing temperature and varies from 2.6 eV to 2.7 eV. However, the oxygen annealing improves crystalline structure. [ABSTRACT FROM AUTHOR]

We report the effect of Ti-doping on structural, morphological, photoluminescence, optical and photoconductive properties of ZnO thin films. Pure and Ti(1, 3 and 5%)-doped ZnO thin films are deposited by the successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction analysis revealed the single-phase hexagonal wurtzite ZnO structure of all the films. Scanning electron microscope images suggest the formation of rod shaped particles in Ti-doped ZnO thin films. Photoluminescence spectra of all the films show emission peaks centered at 398 nm, 413 nm, 438 nm, 477 nm and 522 nm wavelengths. Optical properties support the semiconducting nature of all the films. The optical bandgap values are estimated to be 3.29 eV, 3.26 eV, 3.19 eV and 3.23 eV for ZnO, ZnO:Ti(1%), ZnO:Ti(3%) and ZnO:Ti(5%) thin films, respectively. Photoconductivity study indicates that ZnO:Ti(3%) thin film exhibits high responsivity, external quantum efficiency and detectivity of 0.30 AW-1, 97% and 5.49 × 1010 Jones, respectively, among all the films. The enhanced photoconductivity of Ti-doped ZnO thin films make them useful for optoelectronic applications. [ABSTRACT FROM AUTHOR]

We report the fabrication of Interdigitated Electrode-based thin film Zinc oxide sensor to study volatile organic compounds (VOCs) like 1-butanol, ethanol, acetone, xylene and toluene. The VOC sensing studies were carried out at 50 ppm level and results showed the highest relative response of 28.6% towards 1-butanol at RT (27 °C). Surface characterization of the ZnO structure using XRD, FESEM, EDAX and AFM is discussed which showed uniform hexagonal disc-like structure of ZnO, in hexagonal wurtzite phase of highly crystalline nature. UV–visible spectra showed a maximum absorbance at 360 nm and band gap energy of 3.03 eV (Tauc's plot). ZnO sensor showed good sensitivity for 1-butanol VOC and hence the sensor is tested towards 1-butanol in a custom designed, portable gas chamber with cost-effective instrumentation circuit. It is observed that the sensing results in gas chamber closely matched with that obtained through Keithley instrument. A cost-effective, portable, VOC sensing system can be realized. [ABSTRACT FROM AUTHOR]

The diamond-like carbon- (DLC-) coating technique is used in the sliding parts of automotive engines, among other applications, to reduce friction and wear. In this work, DLC has been coated on the Aluminium 5051 sample to assess the mechanical and tribological properties. A sputtering deposition mechanism is used, and the DLC is coated using a graphite target. The developed DLC coatings are tested for adhesion strength, hardness, chemical composition using XRD, and wear behaviour. The developed DLC thin films have considerably increased the wear behaviour of the Aluminium 5051 sample and have fulfilled the objective of this study. The XRD data indicated the presence of amorphous carbon in the coating with a threefold increase to the hardness of the naked aluminium. This study provides insight into improving the aluminium wear resistance by developing a considerably hard coating. [ABSTRACT FROM AUTHOR]

Terbium (Tb)-doped ZnO thin films were fabricated using the successive ionic layer adsorption and reaction route. Their structural, morphological, optical, and ultraviolet photosensing properties were studied and compared with those of pure ZnO thin films. The x-ray diffraction results illustrate that the pure and Tb-doped ZnO films reveal hexagonal structures with the P63mc space group. The 1% Tb-doped ZnO film shows an increase in the absorption and a decrease in bandgap value from 3.24 eV to 3.15 eV compared to pure ZnO. The photoluminescence results reveal the existence of emission centers at 388, 414, 441, and 477 nm in the fabricated thin films. By increasing the rare earth (Tb) element, the near band edge emission was decreased and correspondingly increased the blue emission due to its 4f orbital energy transition. The photosensing parameters, such as responsivity, external quantum efficiency, and specific detectivity values of the 1% Tb-doped ZnO detector, are 2.21 × 10−1 A W−1, 75%, and 1.84 × 1010 Jones, respectively, which are higher compared to the other fabricated devices due to their better optoelectronic properties. For the 5% Tb-doped ZnO detector, the I–V characteristic curve shows a non-linear behavior, which indicates that a small Schottky barrier is formed in the detector due to widening of the potential barrier and depletion region by Tb. We also investigated the possible energy band diagram of both linear and non-linear (Schottky barrier) behaviors for Tb-doped ZnO detectors. [ABSTRACT FROM AUTHOR]

Thin films with pH sensitivity have been a trendsetter in the current research scenario. Edible films for packaging are comparatively newer ones, where the study uses conventional food materials as a source or precursor to fabricate the films. Starch(S) is one such material that is not much exploited in packaging and pH sensing. Here, the study presents the preparation of a new type of sensitive, intelligent film from starch‐chitin(CHN) composites and adds the anthocyanin pigment extracted from the Butterfly Pea flower (BPE). The combination films are much more sensitive to ammonia and formalin and thus suggested for the detection of adulteration in fish. All the films (S, S/BPE, S/CHN, and S/BPE/CHN) are fabricated by the solution casting method. The addition of 10 wt% CHN results in the enhancement of the thermal and mechanical properties of pH indicator films. Owing to the presence of anthocyanin pigment, the films can change their color changes in pH. The developed starch‐based intelligent films display wide color differences from bright red to green over the 1–12 pH range, which is discriminated by the naked eye. [ABSTRACT FROM AUTHOR]

Aluminum doped zinc oxide (AZO) is becoming an important and alternative transparent conducting oxide (TCO) material for solar photovoltaic applications due to its good electrical and optical characteristics, lower cost and more abundance, non-toxicity and stability in hydrogen plasma when compared to the popular indium tin oxide (ITO). In this work, AZO films are deposited on glass and silicon substrates with direct current (DC) magnetron sputtering using 5N pure Zinc Oxide target doped with 2 wt% Al2O3.The effect of deposition conditions on the structural, electrical and optical properties of the AZO films are investigated. The results demonstrated that the measured thickness of the deposited films are in the range 135- 490 nm. The X-ray diffraction studies reveal that the AZO films exhibit hexagaonal-wurtzite structure with the preferred orientation of grains along the (002) planes and an average crystal size of ~42 nm. At optimized sputter deposition parameters of an electrode distance of ~ 60 mm, substrate temperature of ~ 200 °C, target DC power of ~150 W and working pressure of ~2·10-3 mbar; the AZO films have shown an electrical resistivity of 1.27·10-3 Ω·cm and an average optical transmittance value of 83.76% in the visible range for an optimal film thickness of ~265 nm. Finally HIT Solar Cells with AZO/p-a-Si:H/i-Si:H/n-c-Si/na- Si:H/Al structure have been fabricated by applying the optimized AZO films as front transparent electrodes. It is observed from the preliminary experiments that the fabricated cells have shown an initial photo conversion efficiency of 10.18% with an open circuit voltage (Voc) of 890 mV, short circuit current density (Jsc) of 15.68 mA/cm2 and a fill factor (FF) of ~ 73%. [ABSTRACT FROM AUTHOR]

Cadmium Sulphide (CdS) is II-VI semiconducting material. CdS nanocrystalline film can be developed by chemical bath deposition usingnon aqueous medium. It is used for solar cells, optoelectronic devices, light emitting diodes, etc. The influence of annealing on solid state and optical properties of the films were studied by XRD, FESEM, EDS, AFM, UVVIS, PL. The average grain size of as deposited and annealed CdS films are estimated to be 34nm and 48nm using Scherrer's formula. Compositional analysis indicates the presence of Cd, S and Mo. [ABSTRACT FROM AUTHOR]

We develop an electrothermal transport model for nanocomposite thin films based on self-consistent solution of drift-diffusion and Poisson equations for electrons coupled with diffusive transport of heat. This model is used to analyze the performance of an electronic display the pixels of which are controlled by carbon nanotube (CNT) network thin-film transistors (TFTs). The effect of electrothermal coupling on device performance and steady state temperature rise is analyzed as a function of key device parameters such as channel length, network density, tube-to-substrate thermal conductance, and tube-to-substrate thermal conductivity ratio. Our analysis suggests that device on-current Ion may reduce by 30% for a 1 μm channel length devices due to self-heating. The temperature rise in such devices can be as high as 500 K in extreme cases due to the thermally insulating substrate and the low tube-to-substrate thermal conductance. These results suggest that an appropriate combination of network density, channel length and width should be selected for CNT-TFTs to avoid device temperature rise above acceptable limits. We analyze the effectiveness of active cooling in reducing the temperature and enhancing the performance of the device. We find that the high thermal spreading resistance between the CNT device and the electronic display reduces the effectiveness of forced convective cooling, necessitating the exploration of alternative designs for viable CNT-FET based display technology. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic semiconductors are highly sought in spintronics, which allow not only the control of charge carriers like in traditional electronics, but also the control of spin states. However, almost all known magnetic semiconductors are featured with bandgaps larger than 1 eV, which limits their applications in long‐wavelength regimes. In this work, the discovery of orthorhombic‐structured Ti2O3 films is reported as a unique narrow‐bandgap (≈0.1 eV) ferromagnetic oxide semiconductor. In contrast, the well‐known corundum‐structured Ti2O3 polymorph has an antiferromagnetic ground state. This comprehensive study on epitaxial Ti2O3 thin films reveals strong correlations between structure, electrical, and magnetic properties. The new orthorhombic Ti2O3 polymorph is found to be n‐type with a very high electron concentration, while the bulk‐type trigonal‐structured Ti2O3 is p‐type. More interestingly, in contrast to the antiferromagnetic ground state of trigonal bulk Ti2O3, unexpected ferromagnetism with a transition temperature well above room temperature is observed in the orthorhombic Ti2O3, which is confirmed by X‐ray magnetic circular dichroism measurements. Using first‐principles calculations, the ferromagnetism is attributed to a particular type of oxygen vacancies in the orthorhombic Ti2O3. The room‐temperature ferromagnetism observed in orthorhombic‐structured Ti2O3, demonstrates a new route toward controlling magnetism in epitaxial oxide films through selective stabilization of polymorph phases. [ABSTRACT FROM AUTHOR]

A graphene oxide (GO) nano-additive was incorporated into a polyelectrolyte complex (PEC) to prepare water selective membranes for a water desalination process. The synthesized thin film composites consisted of a PEC-GO separation layer, a microporous poly(vinylidene fluoride) layer, and a non-woven substrate. The crosslinking agent glutaraldehyde (GA) was used to enhance the stability of the PEC composite membranes. The resulting membranes were investigated in nanofiltration systems to examine their permeance and salt rejection efficiency. The results demonstrated that 100 ppm GO in the PEC exhibited a high desalination efficiency on a 1000 ppm NaCl solution. This composite exhibited permeance values in the range of 69–89 kg m −2 h −1 MPa −1 for various salt solutions. The Na 2 SO 4 solution resulted in the highest rejection ratio of 62.1%, followed by the NaCl rejection (38.6%). The MgCl 2 and MgSO 4 solutions had lower rejections of 12.2% and 22.0%. It seems that the GA_PEC-GO composite was more efficient in removing divalent ions than monovalent ions, while maintaining high filtration flux. [ABSTRACT FROM AUTHOR]

Electrical and optical studies have been carried out on aluminium-modified Ge2Sb2Te5 thin films to check its applicability as an active material in optical and electrical memory storage devices. Five polycrystalline bulk samples were prepared with compositions: Alx(Ge2Sb2Te5)1-x; x = 0, 0.08, 0.14, 0.21, 0.25. Amorphous thin films were deposited from the polycrystalline bulk by thermal evaporation. Temperature-dependent resistance shows the increase in crystallization temperature of Ge-Sb-Te films on aluminium addition. Activation energy for conduction, conductivity, optical band gap, coefficient of refraction and extinction coefficient are studied with respect to Al content in both amorphous and crystalline phases of Ge-Sb-Te alloy films. [ABSTRACT FROM AUTHOR]

A class of nanocrystalline alloys, HITPERM (Fe, Co)-M-B-Cu (M=Zr,Hf,Nb, etc.) found to exhibit excellent soft-magnetic properties is being studied for use as a soft-magnetic underlayer for perpendicular recording media. Previously, we reported that HITPERM films of ∼100 nm thickness sputtered at room temperature (RT) and at ∼2.3 W/cm[SUP2]power density had exhibited an amorphous microstructure, which had turned mixed nanocrystalline when prepared at ∼250 °C. However, nanoparticles of FeCo have now been crystallized even at RT without the application of heat, by increasing the sputtering power density to ∼4.5 W/cm[SUP2]. This dramatically improved the 4πM[SUBs] while still maintaining a low coercivity. There was a further slight increase in the 4πM[SUBs] at ∼6.8 W/cm[SUP2]. Moreover, these soft-magnetic properties were maintained even when the substrate temperature was subsequently raised to ∼250 °C. Transmission electron microscopy studies showed the presence of relatively small nanocrystals of the ferromagnetic α'-FeCo (or α-FeCo) phase alone, for both sets of films. Previously, we had reported that the CoCrPt magnetic layer grew with a strong (00·2) texture on amorphous HITPERM. We have now seen that with a thin Ti intermediate layer (∼5 nm) the CoCrPt layer maintained a strong (00·2) texture even on the nanocrystalline HITPERM. Thus, due to their particular nanocrystalline nature, these HITPERM films exhibit much better soft-magnetic properties, while still leading to strong (00·2) texture on the CoCrPt magnetic layer. [ABSTRACT FROM AUTHOR]

Copper oxide films with diverse morphologies are prepared on copper (Cu) substrate by anodization method. The concentration of aqueous NaOH solution used as electrolyte during the anodization process is found as crucial towards formation of different nanostructured films. The reaction temperature impact on chemical composition and morphology of films is also determined. X-ray diffraction patterns disclose that CuO and Cu 2 O are presented in films and the share between both could be altered by changing the NaOH concentration and applied potential. Scanning electron microscopy images unveiled formation of films with diverse morphologies comprised of nanorods, nanoflakes, nanoparticles, and nanoleaves. Raman spectra confirmed the presence of CuO mode and its significant peak intensity has indicated high crystallinity. The prepared films have displayed high solar absorptance (63.5%–77.3%), low thermal emittance (4.5%–5.5%), and better solar selectivity (>14). These results suggest that the anodization method can be employed as a potential technique to prepare facile and affordable solar selective absorbers. [Display omitted] • CuO thin films with diverse morphology were prepared on Cu substrate by anodization technique. • Relative proportion of CuO and Cu 2 O in thin films could be altered by changing the concentration of NaOH and applied potential. • CuO nanorods, nanoflakes and nanoparticles thin films were formed through anodization technique. • High peak intensity modes in Raman spectra revealed high crystalline nature of CuO. • CuO thin films possessed low thermal emittance (4.5%–5.5%), high solar absorptance (63.5%–77.3%) and high solar selectivity (>14). [ABSTRACT FROM AUTHOR]

The phase structure and magnetic behavior of sputter deposited and annealed Ni–Mn–Ga thin films of varying thickness have been studied. The as-deposited films exhibited quasi-amorphous structure having paramagnetic nature at room temperature. After annealing at 873 K for 30 min ferromagnetic ordering is recovered and the quasi-amorphous structure has changed to nanocrystalline structure. At low film thickness (<300 nm), the annealed films exhibited a mixture of cubic austenite (L2 1 ) and martensite phases while at thickness greater than 1000 nm ordered L1 2 phase was observed. The magnetic properties were found to strongly depend on the structure of the constituent phases in the films. [ABSTRACT FROM AUTHOR]

In this paper is aimed to study the augmentation of pool boiling heat transfer characteristics of different surfaces with water, experimentally at atmospheric pressure. There were four surfaces used, viz. untreated (Plain), treated by emery grateno. 2000 and treated with silicon oxide (SiOx) TF surfaces having nano-layer thickness of 100, and 200 nm. The thin film nanocoating was prepared by e-beam evaporation Systems. The surfaces were characterized with respect to contact angle, film thickness and surface roughness. After analyzing the data, it was found that thin film surface is superior to the treated and plain surface in view of boiling heat transfer coefficient. The result found that a maximum of 45.6%, 36.8%, and 10.5% enhancement in heat transfer co-efficient was observed for SiO x TF (200 nm), SiO x TF (100 nm), and treated surfaces respectively compared to plain surface at lower heat flux. Highest enhancement of heat transfer coefficient in thin film surfaces was due to capillary effect, better liquid spreading and high density active nucleate site. [ABSTRACT FROM AUTHOR]

Abstract: Selective solar absorber coatings of copper oxide (CuO) on copper substrates are prepared by room temperature oxidation of copper at different alkaline conditions. The surface morphology and structural analyses of the CuO coatings are carried out by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and Raman spectroscopy techniques. XRD and Raman studies indicated the single phase nature and high crystallinity of the prepared CuO nanostructures. Different CuO nanostructures, viz., nanoneedles, nanofibers and nanoparticles are formed at different alkaline conditions. The influence of reaction time on morphology of the CuO nanostructures is also studied. The thermal emittance values of these nanostructured CuO samples are found to be in the range of 6–7% and their solar absorptances are ranged between 84 and 90%. The observed high solar selectivity values (>12.7) suggest that these coatings can be used as selective absorbers in solar thermal gadgets. [Copyright &y& Elsevier]

Present work reports the effect of substrate on the optical properties of Se92Te4Ag4thin films. Thin films of thickness 2500 Å were prepared by the thermal evaporation of the bulk samples. Amorphous nature of thin films is confirmed by the X-ray diffraction spectra. The transmittance spectra of Se92Te4Ag4thin films were obtained in the spectral region in the range 300–1100 nm. The optical band gap (Eg) and extinction coefficient (k) has been calculated from the absorbance data. The value of refractive index (n) has been determined from Swanepoel's method. The band gap of the film deposited on mica substrate (1.24 eV) is smallest as compared to the band gap of the films deposited on microscopic glass (1.29 eV) and quartz (1.26 eV). The change in value of optical parameters with change in substrate is explained in terms of disorder and defects, which confirms the dependence of optical parameters on types of substrates. [ABSTRACT FROM AUTHOR]

We report the in situ growth of p and n-type graphene thin films by ultraviolet pulsed laser deposition in the presence of argon and nitrogen, respectively. Electron microscopy and Raman studies confirmed the growth, while temperature dependent electrical conductivity and Seebeck coefficient studies confirmed the polarity type of graphene films. Nitrogen doping at different sites of the honeycomb structure, responsible for n-type conduction, is identified using X-ray photoelectron spectroscopy, for films grown in nitrogen. A diode-like rectifying behavior is exhibited by p-n junction diodes fabricated using the graphene films. [ABSTRACT FROM AUTHOR]

This paper reports the influence of silver (Ag) addition on the optical constants of chalcogenide (Se80Te20)100− xAg x (0 ≤ x ≤ 4) thin films. Films of (Se80Te20)100− xAg x (0 ≤ x ≤ 4) glasses were prepared by thermal evaporation of the bulk samples. The transmittance and reflection spectra of amorphous thin films were obtained in the spectral region in the range 400-2500 nm. The optical band gap and the absorption coefficient were calculated from the transmission and reflection data. Swanepoel method has been applied to derive the real and imaginary parts of the complex index of refraction, refractive index, and also the thickness of amorphous films. The dispersion parameters are calculated by using the Wemple-DiDomenico model. The optical constants, i.e., the refractive index, extinction coefficient, absorption coefficient, and optical band gap are determined and their compositional dependence is considered. The results are discussed on the basis of defects and disorders present in chalcogenide systems. [ABSTRACT FROM AUTHOR]

Abstract: Photodoping of Ag into amorphous Ge2Sb2Te5 thin films has been carried out by illuminating thermally evaporated Ge–Sb–Te:Ag bilayers with a halogen lamp in the inert atmosphere at room temperature. Amorphous nature of the as-deposited and photodoped films was confirmed by an X-ray diffraction study. The composition of Ge2Sb2Te5 thin films and the amount of Ag photodiffused have been gathered from electron probe micro-analyzer having a wavelength dispersive spectrometer. Amorphous-to-crystalline transition of the films was induced by thermal annealing and the structural phases were identified by X-ray diffraction. The crystalline temperature of the films was evaluated by temperature dependent sheet resistance measurements. The effects of photodoped Ag concentration on the optical properties of the Ge2Sb2Te5 films have been examined by transmission and reflection spectrometry. It was found that the optical band gap, the sheet resistance and the phase transition temperature increase while the absorption coefficient and extinction coefficient decrease upon incorporation of Ag in Ge2Sb2Te5 system. A correlation between the optical band gap and the electronegativity of the alloys indicates that the optical band gap increases with the decrease of electronegativity. [Copyright &y& Elsevier]

Highlights: [•] Thin films of CuO nanofibers on Cu plates are prepared through a simple method. [•] CuO morphology is controlled by the pH of the reaction medium. [•] The CuO nanostructures are pure and single phase nature. [•] They exhibit high UV–vis absorbance as well as high IR reflectance. [•] The prepared CuO thin films exhibit good solar selectivity values of >13. [Copyright &y& Elsevier]

Abstract: Thin films of amorphous chalcogenide with composition of Ge22Sb22Te56 (thickness d =250nm) and silver film (thickness d =50nm) on top of chalcogenide film were deposited by thermal evaporation technique. Photo-diffusion of Ag into the amorphous Ge2Sb2Te5 thin films has been carried out by illuminating the prepared Ge-Sb-Te:Ag bilayer with halogen lamp. The photo-diffused silver depth profile was traced by means of Time of Flight Secondary Ion Mass Spectroscopy. The films remain amorphous after Ag photo-diffusion into the amorphous Ge2Sb2Te5 films. The composition of Ge2Sb2Te5 thin films and the amount of Ag photo-diffused has been gathered from Electron Probe Micro-analyzer having a Wavelength Dispersive Spectrometer. The composition of the films was found to be very close to the bulk used to deposit films and the amount of Ag photo-diffused was ∼5.20at.%. Changes in the electronic structures of Ge2Sb2Te5 film on Ag photo-diffusion were studied using X-ray photoelectron spectroscopy. The incorporation of silver also increases the optical band gap of the film due to the decrease in the density of defect states on Ag photo-diffusion. [Copyright &y& Elsevier]

Abstract: Bulk sample of (Se80Te20)96Ag4 was prepared by quenching technique. Thin films of (Se80Te20)96Ag4 glasses of different thickness (500–950nm) were deposited on dry clean glass substrates by thermal evaporation technique. Energy dispersive X-ray spectroscopy (EDX) indicates that samples are nearly stoichiometric. X-ray diffraction patterns indicate that they are in the amorphous state. The optical constants, refractive index, absorption index, and optical band gap have been calculated from transmittance and reflectance data in spectral range of 400–2500nm. It has been found that the optical band gap decreases, but the refractive index, extinction coefficient, optical conductivity, real and imaginary dielectric constant increase with increase in thickness of (Se80Te20)96Ag4 thin films. The results are discussed on the basis of rearrangements of defects and disorders in the chalcogenide systems. [Copyright &y& Elsevier]

Abstract: Optical and electrical properties of the (Se80Te20)100− x Ag x (0≤ x ≤4) ultra-thin films have been studied. The ultra-thin films were prepared by thermal evaporation of the bulk samples. Thin films were annealed below glass transition temperature (328K) and in between glass transition temperature and crystallization temperature (343K). Thin films annealed at 343K showed crystallization peaks for Se–Te–Ag phases in the XRD spectra. The transmission and reflection of as-prepared and annealed ultra-thin films were obtained in the 300–1100nm spectral region. The optical band gap has been calculated from the transmission and reflection data. The refractive index has been calculated by the measured reflection data. It has been found that the optical band gap increases, but the refractive index, extinction coefficient, real and imaginary dielectric constant decrease with increase in Ag content. The optical band gap and refractive index show the variation in their values with increase in the annealing temperature. The extinction coefficient increases with increasing annealing temperature. The surface morphology of ultra-thin films has been determined using a scanning electron microscope (SEM). The measured dc conductivity, under a vacuum of 10−5 mbar, showed thermally activated conduction with single activation energy in the measured temperature range (288–358K) and it followed Meyer–Neldel rule. The dc activation energy decreases with increase in Ag content in pristine and annealed films. The results have been analyzed on the bases of thermal annealing effects in the chalcogenide thin films. [Copyright &y& Elsevier]

Abstract: Thin amorphous films of Ge22Sb22Te56 and Ge50Te50 have been prepared from their respective polycrystalline bulk on glass substrates by thermal evaporation technique. The amorphous nature of the films was checked with X-ray diffraction studies. Amorphous-to-crystalline transition of the films has been induced by thermal annealing and the structural phases have been identified by X-ray diffraction. The phase transformation temperature of the films was evaluated by temperature dependent sheet resistance measurement. The chemical structure of the amorphous films has been investigated using X-ray photoelectron spectroscopy and the role of Sb in phase change Ge22Sb22Te56 film is discussed. Survey and core level (Ge 3d, Te 3d, Te 4d, Sb 3p, Sb 3d, O 1s, C 1s) band spectra has been recorded and analyzed. For optical studies, the transmittance and the reflectance spectra were measured over the wavelength ranges 400–2500nm using UV–vis–NIR spectroscopy. The optical band gap, refractive index and extinction coefficient are also presented for thermally evaporated amorphous thin films. [Copyright &y& Elsevier]

Abstract: Surface activity of thermally evaporated amorphous chalcogenide films of Ge2Sb2Te5 has been investigated. Silver (Ag) is readily deposited on such films from appropriate aqueous ionic solution and Ag diffuses into the films upon irradiation with energetic photons. The composition of Ge2Sb2Te5 thin films and the amount of Ag photo-diffused has been gathered from electron probe micro-analyzer having a wavelength dispersive spectrometer. The composition of the films was found to be very close to the bulk used to deposit films and the amount of Ag photo-diffused was ∼ 0.38at. %. X-ray diffraction and temperature dependent sheet resistance studies have been used for the structural analysis of the bulk alloy, as-deposited, Ag photo-diffused and annealed films at different temperatures. The films remain amorphous after Ag photo-diffusion into the amorphous Ge2Sb2Te5 films. The reflectivity, reflectivity contrast and extinction coefficient of the crystalline and amorphous photo-diffused thin films are presented. The optical band gaps of the amorphous and crystalline photo-diffused (Ge2Sb2Te5)100−x Ag x=0.38 phase change thin films have also been calculated from absorption data using UV–VIS spectroscopy. [Copyright &y& Elsevier]

Thin films of SeTeZn ( x = 0, 2, 4, 6 and 10) glassy alloys have been deposited onto a chemically cleaned glass substrate by thermal evaporation technique under vacuum. The analysis of transmission spectra, measured at normal incidence, in the spectral range of 400-2500 nm helped us in the optical characterization of thin films under study. From the analysis of transmission spectra, the optical parameters such as refractive index ( n), extinction coefficient ( k), absorption coefficient (α), real and imaginary dielectric constants ( ε′ and ε″) have been calculated. It is observed that the parameters n, k, ε′, ε″ and α decrease with increase in wavelength ( λ) and increase with Zn content. Optical band gap ( E) has also been calculated and found to decrease with Zn content in SeTeZn glassy system which could be correlated with increase in the density of defect states. [ABSTRACT FROM AUTHOR]

The influence of oxygen vacancies on the transport properties of epitaxial thermoelectric (Sr,La)TiO3 thin films is determined using electrical and spectroscopic ellipsometry (SE) measurements. Oxygen vacancy concentration was varied by ex-situ annealing in Ar and Ar/H2. All films exhibited degenerate semiconducting behavior, and electrical conductivity decreased (258-133 S cm-1) with increasing oxygen content. Similar decrease in the Seebeck coefficient is observed and attributed to a decrease in effective mass (7.8-3.2 me), as determined by SE. Excellent agreement between transport properties deduced from SE and direct electrical measurements suggests that SE is an effective tool for studying oxide thin film thermoelectrics. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we report the effect of Te and Zn incorporation on the density of defect states of two binary Se–In glassy systems. For this purpose, we have chosen here two well known Se90In10 and Se75In25 binary glassy alloys. Thin films of Se90In10, Se75In25, Se75In10Te15 and Se75In10Zn15 glassy alloys prepared by quenching method, were deposited on glass substrate using thermal evaporation technique. Current–voltage characteristics have been measured at various fixed temperatures in the thin films under study. Ohmic behavior was observed at low electric fields while at high electric fields current becomes superohmic. An analysis of the experimental data confirms the presence of space charge limited conduction in Se90In10, Se75In10Te15 and Se75In10Zn15 glassy alloys. It was found that the absence of space charge limited conduction in Se75In25 may be due to joule''s heating at high fields. By applying the theory of space charge limited conduction, the density of defect states near Fermi level was calculated. The peculiar role of the additives (Te and Zn) in the pure binary Se90In10 and Se75In25 glassy alloys is also discussed in terms of electro-negativity difference between the elements involved. [Copyright &y& Elsevier]

The glassy alloy of SeTeZn has been prepared by conventional rapid melt-quenching technique. The glassy nature of the prepared alloy is confirmed through X-ray diffraction (XRD) technique. A thin film of the aforesaid material was prepared by thermal evaporation technique. Coplanar indium electrode was used. Current-voltage ( I- V) characteristics and photoconductivity measurements were obtained. At low electric field, ohmic, and at high electric fields ( E ∼ 10 V/cm), non-ohmic behaviour was observed. An analysis of the experimental data confirms the presence of space charge limited conduction (SCLC) in the glassy material studied in the present case. From the fitting of the data to the theory of SCLC, the density of defect states (DOS) near the Fermi level was calculated. Temperature dependence of conductivity in dark as well as in the presence of light shows that conduction is through a thermally activated process in both the cases. The activation energy is found to decrease with the increase in light intensity. This indicates the shift of the Fermi level with intensity. Transient photoconductivity measurements at different temperatures indicate that the decay of photoconductivity is quite slow, which is found to be non-exponential in the present case, indicating the presence of a continuous distribution of defect states in the aforesaid glassy alloy. [ABSTRACT FROM AUTHOR]