Swift Heavy Ion Induced Functionality In Nanocrystalline CdS Thin Films: Role Of Growth Temperature

¹Department of Physics & Astrophysics, University of Delhi, Delhi 110 007, India

²Department of Physics, Bareilly College, Bareilly 243 005 (U. P.), India

Adv. Mater. Lett., 2015, 6 (9), pp 820-827

DOI: 10.5185/amlett.2015.5921

Publication Date (Web): Sep 06, 2015

Copyright © IAAM-VBRI Press

E-mail:pkumar.phy@gmail.com

Abstract

Influence of growth temperature on swift heavy ion (SHI) induced structural and optical functionality in CdS thin films is explored for photonic applications. Intense green emission is observed in nanocrystalline CdS thin films grown by pulsed laser deposition (PLD) at two different substrate temperatures (T_s): room temperature (RT) and 200 ºC. The role of T_s and its implications on the effect of dense electronic excitation provoked by swift heavy ion irradiation (SHII) on various optical and structural properties of CdS films is investigated under the influence of 70 MeV⁵⁸Ni⁺⁶ ion beam. It reveals from the present studies that T_s may crucially affect the crystalline structure, vibrational and electronic states of the film and thereafter the functionality induced by ion beam. It is found that ion beam is capable to transform structural phase from mixed phase of cubic and hexagonal structure to either pure cubic or pure hexagonal phase of CdS depending upon the pre-existing preferred orientation in pristine film. The modification in crystallite size and band gap due to impact of ion beam is found to be strongly dependent on pre-existing structural phase, as determined by T_s. The studies presented here confirm that initial growth conditions play a key role even after post deposition SHII treatment in selecting precisely the functional behavior of the films.

Keywords

Nanocrystalline CdS thin films, pulsed laser deposition, ion beam irradiation, photoluminescence.