Epitaxial Growth of fcc Fe and Cu Films on Diamond
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EPITAXIAL GROWTH OF fcc FE AND CU FILMS ON DIAMOND
D.P. PAPPAS, J.W. GLESENER, V.G. HARRIS, J.J. KREBS, Y.U. IDZERDA, A.A. MORRISH, AND G.A. PRINZ NAVAL RESEARCH LABORATORY, WASHINGTON, DC 20375
ABSTRACT
The growth of iron and copper films and multilayers on the (100) face of diamond has been achieved and studied by reflection high energy electron diffraction (RHEED), extended x-ray absorption fine structure (EXAFS), ferromagnetic resonance (FMR), and SQUID magnetometry. RHEED and AES studies show that 2-3 atomic layers (AL) of Fe on C(100) forms a continuous film. The films as deposited at room temperature are disordered, and after a 3500 C anneal displays a face-centered cubic structure. Subsequent layers of Cu on this epitaxial Fe film grow as an oriented, single crystal fcc film. FMR and SQUID signals have been observed from the Fe films, showing that they are ferromagnetic.
INTRODUCTION
Stabilization of metastable phases of matter by epitaxial growth on lattice matched substrates has opened an entirely new field of experimental and theoretical physics [1). The use of diamond substrates is appealing due to the extraordinary properties of diamond, i.e. its large band gap, high thermal conductivity, extreme hardness, and desirable optical properties. In the past few years there has been a strong interest in the growth and applications of thin diamond films on various surfaces. Characterization and optimization of the interfacial properties between diamond and various metals is a necessary step in the development of diamond-based electronic devices. An understanding of the magnetic properties of transition metal films on diamond may also provide a means of developing non-volatile magnetic storage devices based on diamond. The epitaxial growth of transition metals on C(100) is feasible due to the close lattice match (a=3.57 A for diamond vs. 3.59, 3.52, and 3.61 for fcc-Fe, Ni, and Cu, respectively), and the fact that the symmetry of the (100) face of the diamond and fcc structures is the same. In fact, recent work by Humphreys, et. al [2], has shown that it is possible to grow continuous, single crystal films of Ni(100) on C(100) by e-beam epitaxy. Cu(100), on the other hand, is more difficult to grow on C(100) due to its tendency to grow in a polycrystalline fashion at room temperature, and ball up into islands upon annealing [3]. Stabilization of single crystal Cu(100) films on an easily prepared, reusable, and insulating substrate such as diamond would be useful in that it would then be possible to prepare Cu(100) surfaces in-situ (rather than resorting to cutting and polishing a Cu single crystal and then sputtering and annealing in-situ). In addition, if magnetic films are to be prepared on Cu(100), subsequent ex-situ measurements such as ferromagnetic resonance (FMR) and magnetoresistance are more easily conducted when there is only a thin film of Cu rather than a macroscopic single crystal substrate. The growth of fcc-Fe at low temperature is also an important objective of this work. It is well known t
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