Nitrogen-doped zinc oxide thin films (ZnO:N) have been realized as a potential matrix for the development of a uric acid biosensor. The correlation between the change in property of the ZnO film with N doping concentration and its biosensing response has been studied. The nitrogen dopant in a ZnO film alters its defects profile, thus improving the charge transfer characteristics and resulting in an enhanced peak oxidation current in the cyclic voltammogram in comparison to that of the pure ZnO film. The studies reveal that the bio-electrode based on the nitrogen-doped ZnO thin film matrix exhibits better sensitivity (1.1 mA mM(-1) cm(-2)) with linearity over a wide range (0.05 mM to 1.0 mM) of uric acid concentration. A comparatively low value (0.10 mM) of the Michaelis-Menten constant (Km) indicates high affinity of the immobilized uricase towards uric acid. The proposed ZnO:N thin films matrix-based uric acid-biosensor has good reproducibility, a long shelf-life (20 weeks) and high selectivity.

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Experimental investigations and first-principle calculations based on density functional theory are effectively combined to shed light on origin of room temperature ferromagnetism in nitrogen doped ZnO (ZnO:N) based intrinsic dilute magnetic semiconductors. ZnO:N thin films grown by pulsed laser deposition show a well defined M-H hysteresis loop at room temperature, reflecting ferromagnetic behavior in contrast to undoped ZnO thin films grown under the same processing condition. Isotropic behavior of magnetism in ZnO:N reveals the dominant contribution of N incorporation on the magnetism and is attributed to p-p interaction between nitrogen and neighboring oxygen atoms having potential for room temperature spintronic applications.

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N doped ZnO (ZnO:N) thin films are prepared by pulsed laser deposition in an oxygen environment using ZnO:N targets with varying nitrogen doping concentrations (1%–10%). The impact of nitrogen incorporation on the microstructural properties of prepared ZnO:N thin films has been studied using Raman scattering. The Raman shift of E2(high) mode towards lower frequencies indicate the substitution of N at O lattice sites (NO). A local vibrational mode corresponding to Zn–N was observed at 480.3 cm−1 in N doped ZnO thin films and highlights the increased strength of the Zn–N bond in the ZnO lattice. Photoluminescence studies reveal the dominant near band edge emission peak in the ultraviolet region and the absence of deep level emission due to defects. The ZnO:N thin films are found to possess room temperature ferromagnetism. N is found to play a significant role in arising ferromagnetism in ZnO and possess a solubility limit of 8% for uniform and homogeneous atomic substitution in ZnO. The present study confirms the promising application of N doped ZnO (ZnO:N) thin films for room temperature spintronics applications.

The electronic structure and properties of carbon incorporated BiFeO3, and resolution to the conductivity aspects of BiFeO3.

Transition from room temperature diamagnetic to ferromagnetic state in N doped ZnO (ZnO:N) films grown by pulsed laser deposition with tunable energy density has been identified. ZnO:N films deposited with moderate laser energy density of 2.5 J/cm2 are single phase and nearly defect free having N dopant substitution at O sites in ZnO lattice, exhibiting intrinsic ferromagnetism. When energy density reduces (<2.5 J/cm2), defects in ZnO:N film degrades ferromagnetism and exhibit diamagnetic phase when grown at energy density of 1.0 J/cm2. Growth kinetics, which in turn depends on laser energy density is playing important role in making transition from ferromagnetic to diamagnetic in ZnO:N films.