AVS 46th International Symposium
    Thin Films Division Thursday Sessions
       Session TF-ThA

Paper TF-ThA4
Microstructure and EL Properties of the ZnS:Mn Luminescence Materials with Co-dopants

Thursday, October 28, 1999, 3:00 pm, Room 615

Session: Ex-situ Characterization
Presenter: Q. Zhai, University of Florida
Authors: Q. Zhai, University of Florida
K.E. Waldrip, University of Florida
J. Li, University of Florida
J.S. Lewis, University of Florida
K. Jones, University of Florida
P.H. Holloway, University of Florida
M. Puga-Lambers, MICROFABRITECH
M. Davidson, MICROFABRITECH
Correspondent: Click to Email
ZnS:Mn thin films were deposited onto glass substrate with pre-deposited indium tin oxide (ITO) and aluminum titanium oxide (ATO) layers, using magnetron sputter source. Transmission electron microcopy (TEM) indicated that the microstructure of the as-deposited films was heavily faulted with fine columnar grains formed through most of the film and a 100nm layer of equiaxed fine grains at the ATO/ZnS:Mn interface. The electroluminescence (EL) properties of the as-deposited films were poor. Post deposition rapid thermal annealing (RTA) with and without co-dopants was studied. KCl co-doped samples showed remarkable improvement in EL brightness after an RTA of 5 min. at 700@super o@C. The threshold voltage was slightly increased. Grain growth from 80nm as-deposited to 200nm after RTA was observed, and the fine-equiaxed-grain crystal layer was removed. Energy dispersive X-ray (EDX) spectra analysis of plan-view transmission electron microscoy (PTEM) samples detected no segregation of any element. Ga@sub 2@S@sub 3@ co-doped samples had no improvement in EL brightness after 5 min. RTA at 800@super o@C, but the threshold voltage was reduced. Grain growth was less than the samples without Ga@sub 2@S@sub 3@, and the fine-equiaxed-grain layer was still visible. EDX results showed Ga segregation at grain boundaries and triple points. When both KCl and Ga@sub 2@S@sub 3@ were introduced into the films through double thermal evaporation/annealing, the sample co-doped with Ga@sub 2@S@sub 3@ at 800@super o@C followed by KCl at 700@super o@C gave the best EL results, but the properties were still inferior to the samples with only a KCl treatment. EDX on PTEM samples detected both K and Ga segregated to grain boundaries and triple points of these samples. The diffusion of co-dopants was analyzed by dynamic secondary ion mass spectrometry (SIMS). Detailed electrical properties of these samples are being studied. A correlation between EL properties and the microstructure will be presented.