Molecular beam Epitaxy of conjugated polymers and their application to electronics

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A year of 1994 is the last year of the research project. We focused on optimization of the MBE growth and optical characterizations and summarized research accomplishments.(1) Optimized MBE growth of copper phthalocyanine (CuPc)Prior to loading into the effusion cell beta-type CuPc powder was heated to remove alcohol. The effusion cell was made of copper, which has a good thermal conductivity and was equipped with a cover with a small hole (a diameter of 1 mm). The temperature of the CuPc in the effusion cell was set to 280ﾟC.Following preheating of the substrates, the shatter of the effusion cell was opened for the growth. Mica, glass (Corning 7059) and Si (111) were used as substrates.(2) CuPc grown on mica and glass substratesFrom the x-ray diffraction analysis, it was found that the planes of CuPc molecules on glass and mica substrates were perpendicular and parallel to the substrate surface, respectively. The optical absorption spectra of the samples were district from that of the … More CuPc powder, suggesting the carrier generation from HOMO to LUMO bands. It is concluded that the CuPc films on mica and glass substrates are crystalline, not molecules.CuPc on Si (111)Prior to loading into the MBE chamber, the dangling bonds of Si (111) surface were terminated with hydrogen atoms by the HF treatment. The grown CuPc interestingly showed bright blue light emission when it was exposed to the ultraviolet light. The intensity of blue light decreased with the illumination time. This suggests a laser-induced structural change. There had not been any reports on blue light emission from the CuPc powder or films.The above experimental results clearly demonstrate that we have established a technique for the MBE growth of CuPc crytals, which is a main objective of the research project. In particular, the established technique for the MBE growth of CuPc on Si has a great potential for development of new functional devices consisting of a combination of inorganic and organic semiconductors. Less