Observation of Heteroepitaxially Grown Organic Ultrathin Layers on Inorganic Substrates by In Situ RHEED and by STM
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OBSERVATION OF HETEROEPITAXIALLY GROWN ORGANIC ULTRATHIN LAYERS ON INORGANIC SUBSTRATES BY IN SITU RHEED AND BY STM MASAHIKO HARA, GARITO*
HIROYUKI SASABE,
AKIRA YAMADA AND ANTHONY F.
The Institute of Physical and Frontier Research Program, Chemical Research (RIKEN), Wako, Saitama 351-01, JAPAN *Permanent Address: Department of Physics, University of Pennsylvania, Philadelphia, PA 19104, USA ABSTRACT system has been An organic molecular beam epitaxy (OMBE) designed and constructed with in situ reflection high-energy electron diffraction (RHEED) specifically for the deposition of the organic molefelar layers under ultrahigh vacuum (UHV), torr. The system is equipped with a portable order of 10UHV chamber which allows easy transfer of the OMBE film samples to a separate UHV scanning tunneling microscopy (STM) system. A structural investigation of heteroepitaxially grown organic ultrathin layers of copper phthalocyanine (CuPc) on inorganic substrates was carried out by the combined UHV system from less than a monolayer of CuPc. INTRODUCTION growth structure A detailed investigation of the initial of ultrathin films is essential to the understanding of the growth mechanism and interface formation between layers of Molecular beam epitaxy (MBE) with ultradifferent materials. high vacuum (UHV) analysis techniques has long been successful the semiconductor primarily in in exploring such problems, field. However, UHV MBE techniques have not been established yet for organic molecular systems which is a prerequisite for realizing current molecular device designs in addition to fundamental interests. The combination of diffraction methods with real space imaging of scanning tunneling microscopy (STM) allows direct Implementastudies of epitaxial layers at the atomic scale. tion requires either having the STM head in the MBE system, or transferring the as-grown samples under UHV atmosphere from the Either choice MBE growth chamber to the separate UHV STM. raises some practical difficulties in the UHV systems that must be solved. Following our previous paper on the newly developed organic molecular beam epitaxy (OMBE) technique [1], here we report growth condition of organa detailed discussion of the initial ic ultrathin layers by in situ reflection high-energy electron and also the complete UHV OMBE system, diffraction (RHEED), introducing a portable UHV chamber for transferring samples from the OMBE chamber to UHV STM and other analysis systems while protecting the sample from contamination. INSTRUMENTATION Figure 1 shows an OMBE system composed ent chambers connected through gate valves. Mat. Res. Soc. Symp. Proc. Vol. 159. ©1990 Materials Research Society
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Fig. 1 Schematic diagram of the combined UHV OMBE system C1:growth chamber, C2:entry chamber, C3:portable c
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