共 66 条
Post-deposition reorganization of pentacene films deposited on low-energy surfaces
被引:54
作者:
Amassian, Aram
[2
]
Pozdin, Vladimir A.
[2
]
Desai, Tushar V.
[1
]
Hong, Sukwon
[1
]
Woll, Arthur R.
[3
]
Ferguson, John D.
[2
]
Brock, Joel D.
[4
]
Malliaras, George G.
[2
]
Engstrom, James R.
[1
]
机构:
[1] Cornell Univ, Sch Chem & Biomol Engn, Ithaca, NY 14853 USA
[2] Cornell Univ, Dept Mat Sci & Engn, Ithaca, NY 14853 USA
[3] Cornell Univ, Cornell High Energy Synchrotron Source, Ithaca, NY 14853 USA
[4] Cornell Univ, Sch Appl & Engn Phys, Ithaca, NY 14853 USA
基金:
美国国家科学基金会;
加拿大自然科学与工程研究理事会;
关键词:
THIN-FILMS;
GATE-DIELECTRICS;
ORGANIC TRANSISTORS;
POLYMER-FILMS;
GROWTH;
SILICON;
SIO2;
NANOSTRUCTURES;
MORPHOLOGY;
AFM;
D O I:
10.1039/b907947e
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
We demonstrate that small-molecule organic thin films of pentacene deposited from thermal and supersonic molecular beam sources can undergo significant reorganization under vacuum or in N-2 atmosphere, beginning immediately after deposition of thin films onto SiO2 gate dielectric treated with hexamethyldisilazane (HMDS) and fluorinated octyltrichlorosilane (FOTS). Films deposited on bare SiO2 remain unchanged even after extended aging in vacuum. The changes observed on low-energy surfaces include the depletion of molecules in the interfacial monolayer resulting in the population of upper layers via upward interlayer transport of molecules, indicating a dewetting-like behavior. The morphology of pristine, as-deposited thin films was determined during growth by in situ real-time synchrotron X-ray reflectivity and was measured again, ex situ, by atomic force microscopy (AFM) following aging at room temperature in vacuum, in N-2 atmosphere, and in ambient air. Important morphological changes are observed in ultra-thin films (coverage < 5 ML) kept in vacuum or in N-2 atmosphere, but not in ambient air. AFM measurements conducted for a series of time intervals reveal that the rate of dewetting increases with decreasing surface energy of the gate dielectric. Films thicker than similar to 5ML remain stable under all conditions; this is attributed to the fact that the interfacial layer is buried completely for films thicker than similar to 5 ML. This work highlights the propensity of small-molecule thin films to undergo significant molecular-scale reorganization at room temperature when kept in vacuum or in N-2 atmosphere after the end of deposition; it should serve as a cautionary note to anyone investigating the behavior of organic electronic devices and its relationship with the initial growth of ultra-thin molecular films on low-energy surfaces.
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页码:5580 / 5592
页数:13
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