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The valence and conduction band offset in FeNiO/CuNiO bilayer film are studied utilizing X‐ray photoelectron spectroscopy and UV–vis spectroscopy. The bilayer film is grown on Si substrate employing ion beam sputtering technique using a mixture of argon and oxygen gases at 25% oxygen partial pressure. From the precise knowledge of the valence band maxima energies and core‐level energy positions in the single‐layer film and the corresponding shifts in the bilayer film, the valence and conduction band offsets are estimated to be 0.8 and 0.3 eV, respectively. From the computed band offset data, a type‐I band alignment is identified at the interface of the grown bilayer film, which facilitates the knowledge of carrier transport mechanism and is highly attractive for the realization of efficient room‐temperature optoelectronic device. [ABSTRACT FROM AUTHOR]

Multiple quantum wells (MQWs) of CdZnO/ZnO are realized, for the first time, by dual ion beam sputtering (DIBS) system at different deposition conditions in terms of ion beam power, substrate temperature, and time cessation between deposition of successive layers. The effects of DIBS deposition conditions are analyzed by secondary ion mass spectroscopy (SIMS) and high-resolution transmission electron microscopy (HRTEM) and discussed systematically. The SIMS analysis has been used for depth profiling of CdZnO/ZnO-based MQWs structure. The deposition of CdZnO/ZnO-based MQW structure performed at 100 °C with time cessation of 30 min between successive layer growth and ion beam power of 14 W has displayed the best results in terms of distinct well and barrier layers formation. This work also includes an analytical study of CdZnO/ZnO-based MQW solar cell (MQWSC), in which a study is performed for solar irradiance dependence of performance parameters to explore the potential use of CdZnO/ZnO-based MQWSC for concentrator solar cell (SC). The short-circuit current density increases from 0.12 to 57.98 mA/cm2, the open-circuit voltage rises from 2.60 to 2.77 V, and the photon conversion efficiency is from 2.85% to 3.04%, as solar irradiance increases from 0.1 to 50 suns. The results show that the performance of SCs can be improved by using concentrators and also explore the possibility of efficiently absorbing short-wavelength photons. [ABSTRACT FROM AUTHOR]

Titanium aluminum nitride (TiAlN) thin films were deposited on Si(1 0 0) substrate using titanium and aluminum targets in 1:1 ratio at various N2 flow rates using ion beam sputtering (IBS) technique. The morphology, particle and crystallite size of TiAlN thin films were estimated by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), and grazing incidence X-ray diffraction (GIXRD) technique, respectively. The SEM images of the TiAlN thin films revealed smooth and uniform coating, whereas AFM images confirmed the particle size varying from 2.5 nm to 8.8 nm, respectively. The crystallite size and lattice strain were observed to vary from 4.79 nm to 5.5 nm and 0.0916 and 0.0844, respectively, with an increase in N2 flow rate in the TiAlN thin films. The X-ray absorption near edge structure (XANES) results showed Ti L, N K and O K-edges of TiAlN coating within a range of 450 eV to 470 eV, 395 eV to 410 eV and 480 eV to 580 eV photon energy, respectively. The electronic structure and chemical bonding of state of c-TiAlN thin film of Ti L, N K and O K-edges were analyzed through semi-empirical curve fitting technique. [ABSTRACT FROM AUTHOR]

CdZnO thin films with a nominal thickness of ~200 nm were grown on c-plane sapphire substrates by dual ion-beam sputtering deposition technique. The effect of substrate temperature (300-600 °C) and gas ambience on structural, morphological, compositional and opto-electronic properties was studied. X-ray diffraction patterns confirmed that all the films were polycrystalline in nature and were preferentially oriented along the c-axis. It was revealed that the films grown at Ar/O ratio of 4:1 were structurally more ordered and the film quality was found to be the best at 500 °C. The compositional studies specify that approximately 11.8 at.% of cadmium were present in the film deposited at 300 °C in Ar-O mixture. Investigations on optical properties by photoluminescence and absorption studies indicate band gap shrinkage with the increase in argon partial pressure and substrate temperature. It was found that photosensitivity of the deposited films was highly dependent on growth conditions. The photosensitivity was found to be 5000-fold higher for CdZnO film grown at 600 °C in Ar-O ambience compared to the best reported result, and this was promising to realize high-performance opto-electronic devices on such CdZnO films. [ABSTRACT FROM AUTHOR]

We have investigated the influence of in situ annealing on the optical, electrical, structural and morphological properties of ZnO thin films prepared on p-type Si(100) substrates by dual ion beam sputtering deposition (DIBSD) system. X-ray diffraction (XRD) measurements showed that all ZnO films have (002) preferred orientation. Full-width at half-maximum (FWHM) of XRD from the (002) crystal plane was observed to reach to a minimum value of 0.139° from ZnO film, annealed at 600 °C. Photoluminescence (PL) measurements demonstrated sharp near-band-edge emission (NBE) at ~ 380 nm along with broad deep level emissions (DLEs) at room temperature. Moreover, when the annealing temperature was increased from 400 to 600 °C, the ratio of NBE peak intensity to DLE peak intensity initially increased, however, it reduced at further increase in annealing temperature. In electrical characterization as well, when annealing temperature was increased from 400 to 600 °C, room temperature electron mobility enhanced from 6.534 to 13.326 cm/V s, and then reduced with subsequent increase in temperature. Therefore, 600 °C annealing temperature produced good-quality ZnO film, suitable for optoelectronic devices fabrication. X-ray photoelectron spectroscopy (XPS) study revealed the presence of oxygen interstitials and vacancies point defects in ZnO film annealed at 400 °C. [ABSTRACT FROM AUTHOR]

Undoped ZnO thin films were grown on p-type Si (1 0 0) substrates at different oxygen partial pressure by dual ion beam sputtering deposition system at a constant growth temperature of 400 °C. The crystallinity, surface morphology, optical, elemental and electrical properties of these ZnO thin films was studied. The minimum value of full-width at half-maximum of the θ-rocking curve obtained from x-ray diffraction of the ZnO (0 0 2) plane, was reported to be 0.1865° from ZnO film grown at 50% of (O2/(O2 + Ar))%. Crystalline property of ZnO films was observed to degrade with the increase in oxygen partial pressure. Photoluminescence measurements demonstrated sharp near-band-edge emission at ~381 nm at room temperature. X-ray photoelectron spectroscopy study revealed presence of oxygen interstitials and vacancies as point defects in ZnO films. Electrical resistivity of ZnO was found to increase with the increase in oxygen partial pressure. [ABSTRACT FROM AUTHOR]

Abstract Thin films of titanium oxide (TiO 2) were prepared by ion beam sputtering at room temperature under various oxygen partial pressure and annealed at 350 °C and higher. Complete target oxidation is observed at O 2 /Ar pressures much lower than the conventional sputtering. The films are analyzed using X-ray diffraction, Raman spectroscopy, optical transmittance, and soft X-ray absorption spectroscopy. As-deposited thin films are all amorphous. Their Ti coordination number is less than that of crystalline phases, anatase and rutile. Upon post-heating above 350 °C in vacuum, films prepared with a ratio O 2 /Ar between 0.25 and 0.66 remain amorphous. Films prepared below this range, develop Ti 6 O 11 and Ti 3 O 5 grains, those prepared above this range become anatase. The band gap of the films varied between 3.12 and 3.36 eV, their refractive index between 2.07 and 2.81. Dielectric modeling of the transmittance spectra shows a broad Gaussian distribution of resonance frequency oscillators suggesting the as-deposited films to be disordered. Highlights • TiO 2 thin films deposited using reactive ion beam sputtering at room temperature. • Complete target oxidation at O 2 /Ar pressures much lower than for conventional sputtering. • Ti coordination in the as-deposited films is less than anatase and rutile. • Annealed films prepared with the O 2 /Ar ratio between 0.25 and 0.66 remain amorphous. • Below this range, develop Ti 6 O 11 and Ti 3 O 5 grains and above this anatase occurs. [ABSTRACT FROM AUTHOR]

Thin films of TiO 2 were grown on quartz substrate at various oxygen partial pressure using ion beam sputtering technique. The surface, structural and optical (linear and nonlinear) properties of the deposited films were studied using X-ray reflectivity, atomic force microscopy and diffraction technique, UV–vis spectroscopy and Z-scan technique, respectively. A transition from amorphous to crystalline nature of the films, decrease in energy band gap and increase in nonlinear absorption coefficient were observed with increase in oxygen partial pressure. The improved nonlinear absorption coefficients and the saturable absorber response of the films suggest the utility of the grown TiO 2 thin films as saturable absorbers. [ABSTRACT FROM AUTHOR]

A systematic growth optimization of Cu 2 ZnSn(S, Se) 4 (CZTSSe) thin films by dual ion beam sputtering system from a single CZTSSe target is presented. It is observed that the ratio of Cu/(Zn + Sn) varies from 0.86 to 1.5 and that of (S + Se)/metal varies between 0.62 and 0.97 when substrate temperature (T sub ) is increased from 100 to 500 °C. The crystal structure of all CZTSSe films are identified to be preferentially (1 1 2)-oriented, polycrystalline in nature, and without the existence of secondary phases such as Cu 2 (S, Se) or Zn(S, Se). The full-width at half-maximum of (1 1 2) diffraction peak is the minimum with a value of 0.12° and the maximum crystallite size 75.11 nm for CZTSSe grown at 300 °C. Morphological investigation reveals the achievement of the largest grain size at T sub = 300 °C. The band gap of CZTSSe thin films at room temperature, as determined by spectroscopic ellipsometry, varies from 1.23 to 1.70 eV, depending on T sub . The optical absorption coefficient of all CZTSSe thin films is >10 4 cm −1 . [ABSTRACT FROM AUTHOR]