Effect of substrate temperature on structural and optical properties of nickel tungsten oxide thin films

Abstract

In this work, we present the substrate temperature induced change in the structural, optical, vibrational and luminescence properties of mixed NiO:WO 3 (95:5) thin films deposited on glass substrates by rf magnetron sputtering technique. X-ray diffraction analysis revealed the onset of crystallization of the films occurred at 300°C. The average optical transmittance of the films varied between 91 and 97 % in the visible region. The refractive index and extinction coefficient of films are found to decrease with increasing substrate temperature. It was observed that the dispersion data obeyed the single oscillator of the Wemple-DiDomenico model, from which the dielectric constants, ratio between free carrier density and free carrier effective mass, plasma frequency, oscillator energy, oscillator strength, and dispersion energy parameters of NiO:WO 3 films were calculated and reported for the first time due to variation in substrate temperature during deposition by rf magnetron sputtering. The micro-Raman result shows two broad peaks corresponding to one-phonon LO mode at 570 cm -1 and two-phonon LO mode at 1,100 cm -1 due to the vibrations of Ni-O bonds and the peak found at 870 cm -1 belongs to the W-O mode. Room temperature photoluminescence (RTPL) study exhibits two characteristic emission peaks at 3.32 eV (374 nm) and 2.93 eV (423 nm), which corresponding to the transition of 3d 8 Ni 2? ions. We have made an attempt to discuss and correlate these results with the light of possible mechanisms underlying the phenomena.

Effect of Cu Metallic Interlayer Thickness on Optoelectronic Properties of TiO2-Based Multilayers Deposited by DC Pulsed Magnetron Sputtering

“…By plotting a graph between the refractive index factor (n 2 À 1) À1 on the y-axis and the square of the photon energy E 2 on the x-axis, a straight line is obtained, as shown in The increase in the E d value is correlated with the increase in the co-ordination number of the atoms resulting from the transformation of TiO 2 thin films from a crystalline to an amorphous structure. 36…”

Copper Molarity Effect on the Optical Properties of Cu2CdSnS4 Quaternary Thin Films

“…This may be due to the fact that increasing the concentration of copper increases the size of the grain, which makes the film surface denser and, consequently, reduces the speed of light diffusion through it [15]. The refractive index values obtained for the quaternary alloy thin films appear to be very suitable for their utilization in photo conversion and optoelectronic devices, as they have a high absorption coefficient and a low refractive index, which increases the efficiency of these devices [27].…”

Controllability of assemblage from WO3·H2O nanoplates to nanoflowers with the assistance of oxalic acid

“…Due to some extraordinary chemical and physical properties, WO 3 has been comprehensively applied and developed in many researches and industries, such as gas sensor [1][2][3], electrochromic [4][5][6], photochromic [7,8], solar energy devices [9,10], photocatalysts [11][12][13][14][15][16] and so on. Since many fundamental properties of semiconductor materials rely not only on the composition but also on the structure, shape and morphology, synthesis of WO 3 with a tunable shape or morphologies has been the subject of insensitive research, such as one-dimensional (1D) like nanorods [17][18][19], nanowires [20,21], and 2D like nanoplates [22], nanofilms [23][24][25], and 3D like nanoflowers [26], nanotrees [27]. In addition, many researchers had proved that the effect of size and structure on the properties of gas sensors [28,29].…”