Shyam, Radhe and Das, Apurba and Dobbidi, Pamu and Singh, Fouran and Vashishtha, Pargam and Gupta, Govind and Nelamarri, Srinivasa Rao (2020) Improved optical properties of ion beam irradiated (K,Na)NbO3 thin films. Journal of Alloys and Compounds, 823. pp. 153794-153804. ISSN 0925-8388

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Abstract

In the present study, we have demonstrated the effect of swift heavy ion (SHI) irradiation on photoluminescence (PL) and time-resolved photoluminescence (TRPL) properties of potassium sodium niobate (KNN) thin films deposited on Si and quartz substrates using RF magnetron sputtering. Ion beam irradiation of crystalline KNN films was carried out at room temperature using 100 MeV Ni ions with different fluences such as 1 x 10(12), 5 x 10(12) and 1 x 10(13) ions/cm(2). Various modes obtained in Raman spectra of films are related to NbO6 octahedron which confirms the crystalline phase of KNN. Moreover, the decrease in peak intensities with ion fluence is attributed to defects produced after SHI irradiation. Xray photoelectron spectroscopy results show the increase in oxygen vacancies after irradiation. The optical properties of pristine and irradiated films were evaluated using UV-Vis-NIR spectroscopy and a significant improvement in optical transmittance upon irradiation was observed. The optical band gap of films is decreased to 3.14 eV upon irradiation at 1 x 10(12) ions/cm(2). PL spectra of films were obtained with excitation wavelength of 274 nm and, the results depict the emission wavelengths (band-to-band or near band edge) of KNN thin films in regime of 313-367 nm (3.96-3.38 eV). The origin of blue and green emission is due to defects created as a result of ion irradiation. The green luminescence evolved at higher fluence (i.e. 1 x 10(13) ions/cm(2)) may be attributed to intrinsic defects such as oxygen vacancies. The obtained Commission Internationale de I'Elcairage (CIE) color coordinates are shifted towards white point in chromaticity diagram as a function of ion fluence. TRPL result reveals the decay lifetime of KNN films in nanosecond regime and, is varied with ion fluence. At fluence of 1 x 10(13) ions/cm(2), film exhibited the minimum average decay lifetime (1.75 ns) which suggests that KNN can be a potential candidate for optical switching, optical display and sensors, and opto-electronic device applications.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Elsevier.
Subjects:	Chemistry > Physical Chemistry Multidisciplinary Materials Science Metallurgy & Metallurgical Engineering
Divisions:	UNSPECIFIED
Depositing User:	Mr. Yogesh Joshi
Date Deposited:	29 Mar 2022 10:36
Last Modified:	29 Mar 2022 10:36
URI:	http://npl.csircentral.net/id/eprint/4756

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