Step-Induced Anisotropic Growth of Pentacene Thin Film Crystals on a Hydrogen-Terminated Si(111) Surface
详细信息 查看全文
- 作者：Susumu Nishikata ; Gen Sazaki ; Toshihiko Takeuchi ; Noritaka Usami ; Shozo Suto ; Kazuo Nakajima
- 刊名：Crystal Growth & Design
- 出版年：2007
- 出版时间：February 2007
- 年：2007
- 卷：7
- 期：2
- 页码：439 - 444
- 全文大小：526K
- 年卷期：v.7,no.2(February 2007)
- ISSN：1528-7505
文摘
We investigate thin film crystals of an organic semiconductor, pentacene (Pn), grown on hydrogen-terminated Si(111) (H-Si(111)) surfaces with various interstep distances to elucidate the effects of vicinal steps of H-Si(111) on the growth ofthe Pn layers. By observing the morphology of the thin films with atomic force microscopy, we conclude that the vicinal stepsinduce significant anisotropy in the growth of the first layers of Pn: dendritic branches evolve in a lower-terrace side (the Si[11
]direction), but a compact shape appears in an upper-terrace side (the Si[
2] direction), although the first layers grow in an isotropicshape on a flat H-Si(111) surface. Furthermore, the growth of the first layers is much faster in the lower-terrace-side direction thanin the upper-terrace-side direction. The anisotropy of the growth increases with decreasing interstep distances of H-Si(111), inparticular 
10 nm. Since such anisotropic growth was observed in a similar way irrespective of the directions of an incident Pnmolecular beam, we conclude that the cause of the anisotropic growth is not the anisotropy of the surface diffusion and admoleculedistribution of Pn molecules. Under the substrate temperature of 30-90 
C, the degree of the anisotropy remained constant withinexperimental error.
]direction), but a compact shape appears in an upper-terrace side (the Si[2] direction), although the first layers grow in an isotropicshape on a flat H-Si(111) surface. Furthermore, the growth of the first layers is much faster in the lower-terrace-side direction thanin the upper-terrace-side direction. The anisotropy of the growth increases with decreasing interstep distances of H-Si(111), inparticular 10 nm. Since such anisotropic growth was observed in a similar way irrespective of the directions of an incident Pnmolecular beam, we conclude that the cause of the anisotropic growth is not the anisotropy of the surface diffusion and admoleculedistribution of Pn molecules. Under the substrate temperature of 30-90 C, the degree of the anisotropy remained constant withinexperimental error.