Epitaxial Growth of C 60 Thin Films using Continuous-wave Laser Molecular Beam Epitaxy
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0965-S14-06
Epitaxial Growth of C60 Thin Films using Continuous-Wave Laser Molecular Beam Epitaxy Seiichiro Yaginuma1,2, Kenji Itaka2,3, Masamitsu Haemori4, Masao Katayama1,3, Yuji Matsumoto1,3, and Hideomi Koinuma2,3 1 Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midoriku, Yokohama, Kanagawa, 226-8503, Japan 2 Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8568, Japan 3 CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama, 3320012, Japan 4 NIMS, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan
ABSTRACT We have fabricated C60 thin films on various substrates (mica, MoS2, HOPG, LiF, NaCl, KBr, KCl and CaF2) by using continuous-wave laser molecular beam epitaxy (CWL-MBE), which is very suitable technique to grow epitaxial organic thin films because of good controllability of evaporation as compared with Knudsen-cell method. The films were evaluated by reflection high-energy electron diffraction with micro channel imaging plate (MCP-RHEED) and atomic force microscopy (AFM). AFM images of the C60 films on mica, MoS2 and HOPG substrates show flat and homogeneous, morphology, and epitaxial growth of the films on mica and MoS2 substrates were observed by RHEED. This result shows mica, MoS2, HOPG substrates are good candidates for epitaxial growth of C60 thin films. INTRODUCTION Recently, π-conjugated semiconductors have much interest since the success of efficient electroluminescent devices and high mobility transistors, and many researchers are trying to fabricate new functional devices with more complicated structures. The primary deposition technique of organic compounds is thermal evaporation with Knudsen cells, but this method has several problems, for example, poor deposition controllability and blocking of pinhole for effusion of evaporated compounds. There is a real need for a new deposition technique for solution of these problems. One of the most problems in depositions with Knudsen cells is pinholes, because adhesion of evaporated compounds decreases the size of the pinhole. The solution to improve deposition controllability should be the deposition method without the pinhole. Hence we have developed new deposition technique of continuous-wave laser molecular beam epitaxy (CWL-MBE) for organic molecular thin films. CWL-MBE provides us with new fabrication technique of high quality organic thin films with quick evaporation response to laser switching and deposition rate corresponding to the laser power [1]. On the other hand, RHEED is a powerful tool for evaluation of thin film growth mode and crystallinity, however π-conjugated molecules are damaged by high-energy electron beam irradiation. Therefore our chamber equips RHEED system with a micro-channel imaging plate
(MCP) to suppress the damage to π-conjugated molecular thin films [2]. C60 grows epitaxially on various substrates and the results are summarized in previous report [3]. In this report, we demonstrate C60 thin film epitaxy on vario
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