Investigation of Low-Damage Sputter-Deposition of ITO Films on Organic Emission Layer

Hao LEI  Keisuke ICHIKAWA  Meihan WANG  Yoichi HOSHI  Takayuki UCHIDA  Yutaka SAWADA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.10   pp.1658-1662
Publication Date: 2008/10/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.10.1658
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Functional Thin Films for Optical Applications)
Category: 
Keyword: 
facing-target sputtering,  indium tin oxide,  low damage,  organic layer,  shield,  γ-electrons,  

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Summary: 
The damage to the organic layer of aluminum (III) bis(2-methyl-8-quninolinato)-4-phenylphenolate (BAlq) film was investigated on the basis of the change in photoluminescence (PL) intensity. To suppress the bombardment of the substrate with high-energy particles such as γ-electrons and negative oxygen ions, we used a facing-target sputtering (FTS) system. A marked reduction, however, of the PL intensity of the organic layer was still observed upon the deposition of an indium tin oxide (ITO) film on the organic film. To reduce this reduction, we proposed the insertion of a sector-shaped metal shield near the target electrode, and we showed its effectiveness in reducing the damage. This reduction of the damage is thought to be caused by the elimination of γ-electrons incident to the organic film surface escaping from the target area near the substrate side. We confirmed that high-energy electron bombardment leads to a significant reduction of PL intensity of the organic layer. This indicates that high-energy electrons incident to the organic film surface play a key role in the damage of the organic layer during the sputtering process.