Ž . Applied Surface Science 154–155 2000 35–39 www.elsevier.nlrlocaterapsusc Ablation study on pulsed KrF laser annealed electroluminescent ZnS:MnrYO multilayers deposited on Si 2 3 E.A. Mastio a, ) , E. Fogarassy b , W.M. Cranton a , C.B. Thomas a a The Nottingham Trent UniÕersity, Department of Electrical and Electronic Engineering, Burton Street, Nottingham NG1 4BU, England, UK b ( ) Laboratoire PHASE UPR du CNRS no. 292 , BP 20, 67037 Strasbourg Cedex 2, France Received 1 June 1999; accepted 24 August 1999 Abstract Ž . Ž The ZnS:Mn active layer of a thin film electroluminescent TFEL device has been annealed under 1.034 MPa 10.34 . bar, 150 psi of argon pressure using a 20-ns pulsed KrF excimer laser. We investigate the effects of multiple shots at various power densities upon the ablation rates of the ZnS:Mn layer. The results are compared to a thermal simulation of the laser-matter interaction using single pulse irradiation, and it is inferred that the cubic to hexagonal transition and melting of ZnS:Mn decrease the ablation rate. q 2000 Published by Elsevier Science B.V. All rights reserved. Keywords: ZnS:Mn; Laser annealing; Ablation; Thin films; Electroluminescence; Thermal model 1. Introduction It is known that annealing is an important step in the manufacturing process of thin film electrolumi- Ž . nescent devices TFEL , since it is required for the activation of luminescent dopant ions and for im- proved crystalline quality. Conventional thermal an- nealing temperatures are limited to 5008C either by the substrate, e.g., glass or by the reduction of the interface state density at the phosphor–dielectric in- wx terface 1 . However, pulsed excimer laser treatment promises a technique that will heat the phosphor layer for very short times with minimal energy ab- sorption at the interfaces and cladding dielectrics, ) Corresponding author. Tel.: q44-115-8482176; fax: q44- 115-9486567. Ž . E-mail address: mastio@phase.c-strasbourg.fr E.A. Mastio . thereby preventing the detrimental modification of the interface states which reduces the device effi- ciency. The viability of KrF laser annealing under Ž . 1.034 MPa 10.34 bar, 150 psi of argon pressure for activating the luminescent dopant of ZnS:Mn phos- phors has recently been demonstrated by the authors wx 2 . Critical to its technological development for electroluminescent application is the definition of the parameters which are needed to successfully anneal the phosphor thin films with no, or minimal ablation. The aim of this paper is to analyse and discuss the effects of multiple irradiation shots at various power densities during laser ablation of a TFEL base layer, Ž . i.e., a stack of 800 nm of ZnS:Mn phosphor and Ž . 300 nm of Y O insulator films deposited onto a 2 3 4-in. silicon wafer. Also to be considered is the evaluation of the remaining phosphor thickness ob- tained under the various annealing conditions since 0169-4332r00r$ - see front matter q 2000 Published by Elsevier Science B.V. All rights reserved. Ž . PII: S0169-4332 99 00379-7