Present work reports the growth of Strontium Barium Niobate (Sr0.75 Ba0.25 Nb2 O6, SBN 75)thin films using Pulsed laser deposition (PLD) technique for possible realization of electrically tunable modulators. Structural and optical properties of grown SBN75 thin film were investigated indicating the growth of high quality polycrystalline and optically transparent. Prism coupling technique was further utilized for coupling the incident laser light λ = 633 nm with the grown SBN75 thin film. The guided EM radiation could be further coupled with the electric field for the realization of EO modulator.

The BiFeO3/BaTiO3 (BFO/BTO) multilayers were deposited on Pt/Ti/SiO2/Si substrates using sol-gel spin coating technique. The electric and magnetic studies on BFO/BTO multilayer structures were carried out for different number of layers. Enhancement in multiferroic properties were seen for all the prepared multilayers as compared to individual BTO and BFO thin films. Maximum value of ferroelectric polarization 71.18 µC/cm2 and saturation magnetization 69.85 emu/cm3 was obtained for multilayer structure having five layers. The observed enhancement in the multiferroic properties of the multilayer system is due to the increased interfacial stress and multiferroic coupling between the alternating layers.

The present work highlights the effect of postdeposition annealing (373–773 K) on the tunability of electrical conductivity of radio frequency sputtered NiOx thin films with both n-type and p-type behavior. The NiOx thin films were polycrystalline with preferred (200) orientation with high optical transmission. The as-grown NiOx thin film exhibits an n-type behavior with room temperature resistivity of 4.80 × 10−3 Ω-cm and majority carrier (electrons) concentration of about 3.90 × 1020 cm−3. Film annealed at 473 K was p-type having resistivity of 1.54 × 10−1 Ω-cm and majority carrier (hole) concentration of about 4.45 × 1018 cm−3. Hall effect and thermoelectric power measurements confirm a transition in electrical conduction from n-type to p-type with postdeposition annealing at 473 K. The observed tunability of electrical conductivity of NiOx thin film will pave way toward realization of p-n homojunction for short wave length optoelectronic device applications.

The effect of tungsten oxide (WO3) thin film thickness on the surface plasmon resonance (SPR) properties have been investigated. WO3 films of varying the thickness (36 nm, 60 nm, 80 nm, 100 nm, 150 nm and 200nm) have been deposited onto Au coated prism (Au/prism) by radio frequency (RF) magnetron sputtering technique. The SPR responses of bilayer films were fitted with the Fresnel’s equations in order to calculate the dielectric constant of WO3 thin film. The variation of complex dielectric constant and refractive index with the thickness of WO3 thin film was studied.

Uric acid biosensor has been developed using tin oxide (SnO2) thin film. The electrochemistry of the developed thin film based electrode is investigated by using cyclic voltammetry. The obtained results demonstrate that the semiconducting SnO2 matrix offers a striking electrocatalytic activity to the immobilized uricase towards the oxidation of uric acid and promotes the transfer of electrons from the active sites of enzyme onto the electrode. SnO2 thin film matrix gives a high sensitivity of 0.2 mA/mM and a shelf life of 20 weeks. Moreover, SnO2 electrode exhibits excellent selectivity and outstanding analytical stability and reproducibility, which enables a reliable and selective determination of uric acid. The SnO2 based uric acid biosensor shows a linear variation in a wide range from 0 to 1.0 mM of uric acid concentration and the Michaelis Menten Constant (Km) is estimated to be 0.28 mM which indicated the high affinity of uricase towards its analyte (uric acid). The results indicate that the SnO2 thin film matrix offers a new and promising platform for the development of novel biosensors.

Zinc oxide (ZnO) thin film deposited onto indium tin oxide (ITO) coated Corning glass substrates using pulsed laser deposition (PLD) technique has been used as a matrix for realization of an efficient urea biosensor after immobilization of urease (Urs) enzyme onto the surface of ZnO. The bioelectrode (Urs/ZnO/ITO/glass) is found to be exhibiting an enhanced sensitivity of 22μΑmΜ−1cm−2 towards urea over a wide detection range of 5-200 mg/dl. The relatively low value of Michaelis menten constant (Km= 0.94mM) indicates high affinity of the immobilized urease towards the analyte (urea). The prepared biosensor retains 90% of its activity for more than 10 weeks. The observed enhanced response characteristics of bioelectrode are attributed to the growth of the matrix (highly c-axis oriented ZnO thin film) with desired surface morphology and high electron communication feature. The results confirm the promising application of PLD grown ZnO thin film as an efficient matrix for urea detection.

Ultraviolet (UV) photoconductivity in pure ZnO thin films and metal (Ag, Au, Pt) nanoparticles (NPs) dispersed on ZnO thin films based UV photodetectors biased at 5 V for ultra violet radiation of λ = 365 nm and intensity = 24 µwatt/cm2 has been studied. All the three metal (Ag, Au, Pt) NPs synthesized by Polyol process when dispersed on the surface of 100 nm thin ZnO film results in enhanced photoconductive gain (K) in comparison to pure ZnO (3.1×103). An increase of about an order in K has been obtained in the case of Ag NPs/ZnO and Au NPs/ZnO UV photodetectors ( K = 6.9×104 and 5.3×104 respectively). On the other hand, Pt NPs enhance K by about two orders (5.0×105). Such an enhanced photoconductive gain has been achieved due to the lowering of dark current after dispersing the metal NPs on the surface of ZnO and increased photocurrent upon UV illumination. This may be attributed to the plasmon propagating property in metal NPs which enhances the light trapping through optical absorption in ZnO thin film surface (high photo current).

SnO2 based sensor structures prepared by rf magnetron sputtering technique have been studied for detecting H2 gas. Pd catalyst was integrated onto the SnO2 thin film in the form of clusters and nano-particles to obtain enhanced sensing response characteristics. The prepared sensor structures have been studied over a temperature range of 50-250°C for sensing response towards 500 ppm H2 gas. The sensor with Pd catalyst dispersed in the form of nanoparticles was found to exhibit an enhanced sensing response of 1.9×103 at a relatively low operating temperature of 150°C with a fast response time of 2 s and recovery time of 65 s towards 500 ppm H2 gas. The origin of enhanced sensing response is identified in the light of the enhanced spill over of H2 gas molecules on the uncovered surface of SnO2 thin film.

Ultraviolet photoconductivity in Copper doped ZnO (Cu:ZnO) thin films synthesized by sol-gel technique is investigated. Response characteristics of Pure ZnO thin film and Cu:ZnO thin film UV photodetector with 1.3 at. wt % Cu doping biased at 5 V for UV radiation of λ = 365 nm and intensity = 24 µwatt/cm2 has been studied. Cu:ZnO UV photodetector is found to exhibit a high photocoductive gain (K = 1.5×104) with fast recovery (T90% = 23s) in comparison to pure ZnO thin film based photodetector (K = 4.9×101 and T90% = 41s). Cu2+ ions have been substituted in ZnO lattice which has been confirmed by X-ray diffraction (XRD) and Raman spectroscopy leading to lowering of dark current (Ioff ∼ 1.44 nA). Upon UV illumination, more electron hole pairs are generated in the photodetector due to the high porosity and roughness of the surface of the film which favours adsorption of more oxygen on the surface of the photodetector. The photogenerated holes recombined with the trapped electrons, increasing the concentration of photogenerated electrons in the conduction band enhancing the photocurrent (Ion ∼ 0.02 mA) of the Cu:ZnO photodetector.

Temperature dependent optical properties of RF-sputtered c-axis oriented ZnO:N thin film have been investigated. Surface Plasmon modes are excited at the metal-dielectric interface in the Kretschmann-Reather configuration using prism coupling technique. Effect of ZnO:N thin film deposited over Prism-Au structure on the SPR reflectance is studied over a wide range of temperature from 300–500 K at 633 nm wavelength. The value of dielectric constant of ZnO:N film obtained by fitting the experimentally obtained data with the theoretically generated SPR curve at the optical frequency is found to increase linearly with temperature. The increase in dielectric constant (4.03 to 4.11) with increase in temperature from 300 K to 500 K indicates a promising application of the system as an efficient low-cost temperature sensor.

Transparent p-n hetero-junction diodes are fabricated using, p-type NiO and n-type ZnO thin films deposited onto a Pt/Ti/glass substrate utilizing RF sputtering technique. The prepared hetero-junctions are studied for the structural, electrical and optical properties and the effect of post-deposition annealing is investigated through I-V measurements and XRD analysis. The as deposited hetero-junction is found to be giving ohmic behaviour while with post-annealing treatment it result in rectification with a ratio of forward-to-reverse current as high as 15 in the range -1.0 to 1.0 V. Forward threshold and the reverse breakdown voltages are found to be about 0.5 and -2.7 V, respectively. The forward-bias I-V characteristics are dominated by the flow of space-charge-limited current with an optical transmission of above 50 % in the visible region important for the transparent electronic device fabrication.

C-axis oriented lithium niobate (LiNbO3) films were deposited by pulsed-laser deposition on silicon using a transparent conducting interlayer of aluminum (Al)-doped zinc oxide (ZnO). Only two x-ray diffraction reflections corresponding to (006) and (0012) planes of LiNbO3 were observed in the films deposited at a 100-mTorr oxygen pressure and a 450–500 °C substrate temperature. Presence of sharp modes corresponding to E(TO) and A(LO), and absence of any superfluous peaks mainly around 900–905 cm−1 in the Raman spectra confirmed the formation of textured LiNbO3 film. Measured value of direct current and alternate current (AC) conductivities and dielectric constant are 8.6 × 10-12 Ω−1cm-1, 1.16 × 10-6 Ω−1cm-1, and 29.3, respectively, at room temperature. Behavior of dielectric constant and AC conductivity with frequency and temperature are close to the reported single-crystal data.