Lattice misfit versus performance of thin film electroluminescent structures

Citation
Ea. Mastio et al., Lattice misfit versus performance of thin film electroluminescent structures, J APPL PHYS, 89(3), 2001, pp. 1605-1611
Citations number
27
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF APPLIED PHYSICS
ISSN journal
00218979 → ACNP
Volume
89
Issue
3
Year of publication
2001
Pages
1605 - 1611
Database
ISI
SICI code
0021-8979(20010201)89:3<1605:LMVPOT>2.0.ZU;2-M
Abstract
Thin polycrystalline electroluminescent thin films (TFEL) of ZnS:Mn (phosph or) and Y2O3 (insulator) were deposited individually or as multilayers onto Si (100) substrates. Their crystallinity and the luminescent efficiency of the phosphor films were investigated at varying thermal annealing temperat ures. It is shown that the luminescent quality of the phosphor layer increa ses up to 700 degreesC, whereas the electroluminescence operating intensity of TFEL devices saturates at 500 degreesC. The structural analysis of the insulating and phosphor layers shows that they recrystallize at annealing t emperatures of, respectively, 500 and 600 degreesC, and that their lattice misfit doubles at processing temperatures>=500 degreesC. Since TFEL devices should benefit from enhanced luminescence efficiency and crystallinity at high annealing temperatures, we suggest that the lack of improvement in dev ice performance beyond 500 degreesC is due to interface alterations. Accord ing to previous works, we propose that the lattice misfit increase between the phosphor and dielectric thin films modifies the morphology of the phosp hor-insulator boundary inducing a modification of the interface states dens ity, and hence, modifying high field electron transport properties of TFEL devices. (C) 2001 American Institute of Physics.