In-depth variations of diamond structures on Pt(111) investigated by confocal Raman spectroscopy

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In-depth variations of diamond structures on Pt(111) investigated by confocal Raman spectroscopy Mikka Nishitani-Gamoa) Core Research for Evolutional Science and Technology (CREST), c/o National Institute for Research in Inorganic Materials (NIRIM), 1-1 Namiki, Tsukuba, Ibaraki 305, Japan; and Toppan Printing Co. Ltd., Materials Research Laboratory, 4-2-3 Takanodai-Minami, Sugito, Saitama 345, Japan

Takeshi Tachibana and Koji Kobashi Electronics & Information Technology Laboratory, Kobe Steel Ltd., 1-5-5 Takatsukadai, Nishi-ku, Kobe 651-22, Japan

Isao Sakaguchi and Toshihiro Andob) Core Research for Evolutional Science and Technology (CREST), c/o National Institute for Research in Inorganic Materials (NIRIM), 1-1 Namiki, Tsukuba, Ibaraki 305, Japan (Received 7 April 1997; accepted 31 July 1997)

We have characterized heteroepitaxial diamond films on Pt(111) using the nondestructive technique of confocal Raman spectroscopy to investigate the variation in structure and strain with depth. The spectral depth profiles of heteroepitaxial diamond showed the diamond peak at 1332–1335 cm–1 and four bands centered at 1230 cm–1 , 1470–1490 cm–1 , 1530–1580 cm–1 , and 1640 cm–1 near the surface. The diamond peak shifted to the single crystal peak position at 1332 cm–1 as the linewidth was broadened with free surface proximity. The compressive strain in the heteroepitaxial diamond crystal decreased and turned into the random strain. At the same time, the Raman band at 1470–1490 cm–1 grew in intensity. The constituents of non-diamond phase in the heteroepitaxial growth regions are different from those formed in the randomly oriented regions.

I. INTRODUCTION

The realization of diamond heteroepitaxial growth is of great scientific and technological importance. Recently, Shintani succeeded in obtaining a highly oriented, highly coalesced diamond films on the platinum (111) surface by microwave plasma chemical vapor deposition (MPCVD).1 Tachibana and co-workers also obtained highly oriented, highly coalesced diamond films on the bulk single crystal platinum (111) surface by MPCVD.2 On the other hand, several groups have successfully obtained oriented growth of diamond on silicon,3–5 and also on silicon-related materials such as a –SiC6 and b –SiC.7,8 Oriented diamond nucleation has been suggested to originate from a chemically reacted interface between carbon and silicon.9 Intriguingly, heteroepitaxial diamond growth on metallic substrates has been shown to be possible even though the nature of the interfacial bonds is rather different. These results indicate that the underlying mechanism of heteroepitaxy is far from clear. Actually, very little is known about the mechanistic details of either diamond nucleation or growth. An in-depth understanding of the mechanism of

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Visiting researcher; e-mail: [email protected] Corresponding author; e-mail: [email protected]

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http://journals.cambridge.org

J. Mater. Res., Vol. 13, No. 3, Mar 1998

Downloaded: 08 Apr 2015

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