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Control of the deposition parameters of GaN and Ga(1-x)Mn(x)N hetero-epitaxial films prepared by the RF magnetron sputtering technique


The basic and applied research about GaN films and related devices are the main topics related to semiconductor development at present, while Ga(1-x)Mn(x)N (x in the 0,03-0,07 range) compounds are promising candidates for the development of electronic devices in which the control of electron spin is possible (spintronics). Reports found in the literature in the last three years have shown that the RF magnetron sputtering technique can produce high quality hetero-epitaxial GaN films, making it competitive with more complex techniques like metalorganic chemical vapor deposition (MOCVD) and plasma assisted molecular beam epitaxy (PAMBE). Besides its simplicity, RF magnetron sputtering is compatible with the growing of GaN at smaller substrate temperatures, allows the choice to use or not hydrogen in the deposition process, and simplify the introduction of controlled quantities of Mn during the preparation of Ga(1-x)Mn(x)N. In this proposal we are interested in growing GaN and Ga(1-x)Mn(x)N films using the RF magnetron sputtering with effective control of the deposition parameters. A sputtering system previously build will be completed to allow plasma emission spectroscopy and mass spectrometry. The capabilities of substrate polarization, substrate temperature control, and direct auto-bias target voltage measurement will also be implemented. The better control of the deposition parameters and the more detailed information about the film growth are expected to allow a better understanding about the physical properties of the produced films. Test samples deposited using the present available conditions have produced nanocrystalline GaN and Ga(1-x)Mn(x)N, with crystallites having wurtzite structure. The test films have shown excellent mechanical and optical properties, but do not exhibit ferromagnetic characteristics, even at temperatures as low as 2K. Preliminary EXAFS measurements indicate that the local structure of Mn bonds is similar to the Ga sites, similarly to the site positions occupied by Mn in ferromagnetic samples. No indication of Mn clustering was found in the EXAFS measurements. So the lack of magnetic ordering in these samples is probably related to structural disorder. The use of co-sputtering method proposed to introduce Mn to the hetero-epitaxial grown compound have potential to be innovative among the existing techniques of Ga(1-x)Mn(x)N deposition. Our aim is the growth of hetero-epitaxial GaN and Ga(1-x)Mn(x)N films by RF magnetron sputtering having high homogeneity and low defect density. We will also focus on the understanding of the role of the main deposition parameters on the structural properties. As application of the optimized films we will evaluate their effectiveness to produce diluted magnetic semiconductors with ferromagnetic characteristics. (AU)

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Scientific publications (6)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
GOMES, M. C.; LEITE, D. M. G.; SAMBRANO, J. R.; DIAS DA SILVA, J. H.; DE SOUZA, A. R.; BELTRAN, A.. Thermodynamic and electronic study of Ga-1 _ xMnxN films. A theoretical study. Surface Science, v. 605, n. 15-16, p. 1431-1437, . (05/02249-0)
LEITE, D. M. G.; LI, T.; DEVILLERS, T.; SCHIABER, Z. S.; LISBOA-FILHO, P. N.; BONANNI, A.; DIAS DA SILVA, J. H.. Columnar microstructure of nanocrystalline Ga1-xMnxN films deposited by reactive sputtering. Journal of Crystal Growth, v. 327, n. 1, p. 209-214, . (05/02249-0)
ANGELICO, JOAO C.; PEREIRA, ANDRE L. J.; DE ARRUDA, LARISA B.; DIAS DA SILVA, JOSE H.. Electrical transport mechanisms and structure of hydrogenated and non-hydrogenated nanocrystalline Ga1-xMnxAs films. Journal of Alloys and Compounds, v. 630, p. 78-83, . (05/02249-0, 12/21147-7)
PEREIRA, ANDRE L. J.; DA SILVA, J. H. DIAS. Disorder effects produced by the Mn and H incorporations on the optical absorption edge of Ga1-xMnxAs:H nanocrystalline films. Journal of Non-Crystalline Solids, v. 354, n. 52-54, p. 5372-5377, . (05/03463-5, 05/02249-0)
SCHIABER, ZIANI S.; LEITE, DOUGLAS M. G.; BORTOLETO, JOSE R. R.; LISBOA-FILHO, PAULO N.; DA SILVA, JOSE H. D.. Effects of substrate temperature, substrate orientation, and energetic atomic collisions on the structure of GaN films grown by reactive sputtering. Journal of Applied Physics, v. 114, n. 18, . (05/02249-0, 12/21147-7, 11/22664-2)
LEITE, D. M. G.; PEREIRA, A. L. J.; IWAMOTO, W. A.; PAGLIUSO, P. G.; LISBOA-FILHO, P. N.; DA SILVA, J. H. D.. Magnetic characteristics of nanocrystalline GaMnN films deposited by reactive sputtering. SOLID STATE SCIENCES, v. 17, p. 97-101, . (05/02249-0)

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