Photoluminescence in Nanocrystalline Films of (Cd0.8-Zn0.2)S : Eu

International Journal of Research and Scientific Innovation (IJRSI) | Volume V, Issue I, January 2018 | ISSN 2321–2705

Photoluminescence in Nanocrystalline Films of (Cd_0.8-Zn_0.2)S : Eu

Sandhya Pillai*, Dev Jyoti Lilhare

Department of Physics, Christian College of Engineering and Technology, Kailash Nagar, Bhilai. (C.G.), India.

Abstract: Europium doped nanocrystalline films of (Cd_0.8-Zn_0.2)S are prepared by chemical bath deposition method (using capping agents) on glass substrates at different temperatures (60ºC, 80ºC and 100ºC). Their optical absorption spectra and photoluminescence (PL) emission spectra are studied and compared with that of the bulk film (prepared at 60ºC without capping agents). Blue shift in the absorption edge is observed in the nanocrystalline film in comparison to that of bulk indicating quantum confinement effect. The values of optical band gap obtained from Tauc’s plots have been found to be 2.41eV for the bulk film and in the range 2.81eV to 2.95eV for the different nanocrystalline films prepared at different temperatures. The value of band gap decreases with increasing bath temperature. The grain sizes obtained from these studies also lie in the nano range. Photoluminescence emission spectra show a shift in emission peak towards shorter wavelength suggesting particle size reduction. A less intense peak at around 615nm is also observed which may be due to the ⁵D₀ –> ⁷F₂ transition in Eu³⁺ ions. Emission intensity is maximum for deposition at 60º C.

Keywords: Photoluminescence, chemical deposition, nanocrystalline property.

I. INTRODUCTION

Nanocrystalline materials have attracted many material researchers due to its enhanced thermal, electrical and optical properties when compared to that of bulk materials. These materials are becoming increasingly interesting for optoelectronics and photonics. The electronic and electrical properties of such materials show a remarkable change as the particle size approaches that of its excitonic Bohr radius and then electrons and holes are subject to quantum confinement effects [1, 2] due to their large surface to volume ratios resulting in high density of surface states. Nanoscale semiconductors show interesting electro-optical properties and catalytic behavior [3].

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