Delhi Technological University

About: Delhi Technological University is a education organization based out in New Delhi, India. It is known for research contribution in the topics: Computer science & Control theory. The organization has 4427 authors who have published 6761 publications receiving 71035 citations. The organization is also known as: Delhi College of Engineering & DTU.

Ultraviolet radiation detection by barium titanate thin films grown by sol–gel hydrothermal method

Abstract: Ultraviolet (UV) photodetector using ferroelectric barium titanate, BaTiO3 thin film has been prepared successfully. BaTiO3 (BTO) this film is deposited by sol–gel hydrothermal (SG-HT) method. The deposited BTO films were found to be polycrystalline having a band gap of about 3.51 eV. The photoconductive gain (K = Ion/Ioff) of bare BTO based photodetector was found to be 8.36 × 102 for UV radiation (λ = 365 nm and intensity = 24 μW/cm2). The modifier, tungsten (W) in the form of both thin overlayer and uniformly distributed circular dotted structures (600 μm diameter) were integrated with the surface of BTO thin film by rf-magnetron sputtering technique to improve the photoresponse characteristics. The photoconductive gain was enhanced to about two orders of magnitude (1.84 × 104) after integration of W modifier in the form of circular dots. The significant enhancement in photoresponse for W(dots)/BTO photodetector is related to the twin effect of (1) reduction in dark current (Ioff) due to formation of schottky junction between the oxide (BTO) and metal (W), and (2) enhancement in photocurrent (Ion) due to high absorption of UV radiation on the detector surface.

Judd-Ofelt Parameterization and Luminescence Characterization of Dy3+ Doped Oxyfluoride Lithium Zinc Borosilicate Glasses for Lasers and w-LEDs

Abstract: In this work, Oxyfluoride Lithium Zinc Borosilicate glasses of varying Dy3+ ions concentration were prepared by using a melt quench technique. The optical and luminescence characteristics of Dy3+ ions were analyzed by XRD, absorption and emission spectroscopy. The Judd-Ofelt (J-O) parameters estimated by correlating absorption spectral measurements. The emission profiles displayed three principle bands in blue, yellow, red regions and quenching was detected at 1 mol% of Dy3+ ions. The radiative properties were evaluated for the protuberant luminous levels of Dy3+ ions within the ambit of J-O theory. The color coordinates at 351 nm pumping wavelength provide the worthy white emission. The decay profiles of 4F9/2→6H13/2 showed exponential nature up to 1 mol% and non-exponential elsewhere. It has been observed that 1.0 mol % Dy3+ ions doped OFLZBS glasses are aptly fit for white light generation. This observation showed that as-quenched glasses may have great potentials for lasers and w-LEDs applications.