Heat and fluid flow in high-power LED packaging and applications

Tailoring optical bandgap of ZnO nanostructured thin films doped with different elements facilitates potential material for photonic applications. Different methods of fabrication process result in different optical and structural properties for the same amount of Mg content. Therefore, details investigation of structural and optical parameters, and their correlation need to be revealed to utilize the fabricated thin films. In this work, Mg-doped ZnO thin film of 200 nm thickness was fabricated by sol-gel spin coating method on a glass substrate for four different Mg content levels. Multiple layers were deposited by a spin coater to increase the film thickness. The prepared thin films were characterized by SEM, XRD, EDS, and UV–Vis spectroscopy. The spectroscopic analysis showed a uniform crystalline nanostructured surface with less structural defects, enhanced transmittance, and higher optical bandgap than that of pure ZnO nanostructured thin film. Change of Mg content from 2% to 8% facilitated tuning of bandgap in the range of 3.30–3.39 eV. Changing trend of structural and optical parameters with Mg content showed non-linear, non-monotonic relation. In-depth analysis of structural and optical properties provides crucial information to form a better view about bandgap dependency on structural parameters.

Influence of Mg content on tailoring optical bandgap of Mg-doped ZnO thin film prepared by sol-gel method

The influence of Al doping on the photocatalytic activity of nanostructured ZnO: The role of adsorbed water

Environmental pollution from human and industrial activities has received much attention as it adversely affects human health and bio-diversity. In this work we report efficient visible light photocatalytic degradation of phenol using supported zinc oxide (ZnO) nanorods and explore the role of surface defects in ZnO on the visible light photocatalytic activity. ZnO nanorods were synthesized on glass substrates using a microwave-assisted hydrothermal process, while the surface defect states were controlled by annealing the nanorods at various temperatures and were characterized by photoluminescence and X-ray photoelectron spectroscopy. High performance liquid chromatography (HPLC) was used for the evaluation of phenol photocatalytic degradation. ZnO nanorods with high surface defects exhibited maximum visible light photocatalytic activity, showing 50% degradation of 10 ppm phenol aqueous solution within 2.5 h, with a degradation rate almost four times higher than that of nanorods with lower surface defects. The mineralization process of phenol during degradation was also investigated, and it showed the evolution of different photocatalytic byproducts, such as benzoquinone, catechol, resorcinol and carboxylic acids, at different stages. The results from this study suggest that the presence of surface defects in ZnO nanorods is crucial for its efficient visible light photocatalytic activity, which is otherwise only active in the ultraviolet region.

Controlled Defects of Zinc Oxide Nanorods for Efficient Visible Light Photocatalytic Degradation of Phenol

Structural, morphological and optical behaviour of PVP capped binary (ZnO)0.4 (CdO)0.6 nanoparticles synthesised by a facile thermal route

Structural, optical and electronic structure studies of Al doped ZnO thin films

Effect of post annealing temperature on structural and optical properties of ZnCdO thin films deposited by sol–gel method

Effect of substrate temperature and oxygen partial pressure on structural and optical properties of Mg doped ZnO thin films

The valence and conduction band offsets of Zn1−xCdxO/ZnO hetero-junctions deposited by pulsed laser deposition technique were estimated by X-ray photoelectron, valence band, and UV-visible spectroscopy. Type-II band alignment (staggered gap) with ratios of conduction band to valence band offsets (ΔEC/ΔEV) was found to be 0.77 and 0.59 for Zn0.95Cd0.05O/ZnO and Zn0.90Cd0.10O/ZnO hetero-structures, respectively, which can be used in longer wavelength regime optoelectronic devices. The higher value of valence band offset as compared to conduction band offset suggests that the transport at interface is mainly due to electrons.

Band offset studies in pulse laser deposited Zn1−xCdxO/ZnO hetero-junctions

The 7 wt % Cd doped and 15 wt % Mg doped ZnO thin films were deposited on quartz substrate by pulse laser deposition system. The structural and optical properties of the prepared ZnO, Cd:ZnO and Mg:ZnO films were investigated by X-Ray diffraction (XRD), photoluminescence and UV-Vis spectroscopy techniques. XRD results indicate that the doped ZnO films maintain wurtzite crystal symmetry without any defects and are oriented along c- axis. Photoluminescence studies show a sharp band edge emission peak at 384 nm for pure ZnO film. This peak is blue shifted to 381 nm with Cd doping and red shifted to 395 nm with Mg doping. UV visible absorption studies reveals a decrease in band gap with Cd doping and an increase in band gap with Mg doping.

https://iopscience.iop.org/article/10.1088/1742-6596/534/1/012047/pdf

B. C. Joshi

Papers

Structural, optical and electronic structure studies of Al doped ZnO thin films

Effect of post annealing temperature on structural and optical properties of ZnCdO thin films deposited by sol–gel method

Effect of substrate temperature and oxygen partial pressure on structural and optical properties of Mg doped ZnO thin films

Band offset studies in pulse laser deposited Zn1−xCdxO/ZnO hetero-junctions

Structural and optical properties of Cd and Mg doped zinc oxide thin films deposited by pulsed laser deposition