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Surface chemical phenomena and growth of films
Thin Solid Films, 85 ( 1981 ) 263-264
263
PREPARATION AND CHARACTERIZATION
SURFACE CHEMICAL PHENOMENA AND GROWTH OF FILMS* P. B. BARNA
Research Institute for Technical Physics of the Hungarian Academy of Sciences, 1325 Budapest, P.O. Box 76 (Hungary)
To obtain an understanding of the different structures and properties of real thin films, surface chemical interactions taking place between the nascent growing film surfaces and impinging foreign species (impurities) should be considered. Active impurities have been found to influence the atom-by-atom building process of films. Surface defects on the growing films (e.g. steps, kinks and vacancies) represent the sites of film growth, i.e. sites to which new adatoms can bind, and at the same time they are the very active sites of surface chemical interactions ~. During film formation these sites are continuously produced by the growth mechanisms. Consequently, the most active initial stage of surface chemical interactions can take place during the dynamic development of films. In this paper surface chemical interactions contributing to the condensation of foreign species or to the development of new stable phases or compounds will be discussed. The crystal face anisotropy in the microchemical activity found by Martinson et al. 2 and Michel et al. 3 results in the anisotropy in crystal growth. I n s i t u experiments have shown the accumulation of foreign species by the moving growth steps onto the surfaces of growing crystals and the development of layers which cover the surfaces either partly or completely4' 2. In this way the growth and coalescence of crystals are governed by their orientation and by the development of surface-covering layers6. The surface chemical interactions taking place at the very active surface sites on the nascent film surface 7 and the accumulation of their products by the moving steps make the developing structure and its properties very sensitive to impurities, even at rather low contamination levels s. These impurities can be very active in influencing the structure and properties as well as in causing the development of structural peculiarities for which crystal face anisotropy in the microchemical activity exists. 1 G.A. Somorjai, Adv. Catal.(1977) 1. 2 3 4
C . W . B . Martinson, S. A. Flodstr6m, J. Rundgren and P. Westrin, Surf Sci., 89 (1979) 102. R. Michel, J. Castaldi, C. Allasia, C. Jourdan and J. Derrien, Surf Sci., 95 (1980) 102. J . F . P6cza, A. Barna, P. B. Barna, I. Pozsgai and G. Radn6czi, Jpn. J. Appl. Phys., Suppl. 2, Part 1 (1974) 525.
*Abstract of a paper presented at the International Summer School on Processes of Thin Film Formation, Fony6d, Lake Balaton, Hungary, September 28 to October 4, 1980. 0040-6090/81/0000-0000/S02.50
g;. Elsevier Sequoia,'Printed in The Netherlands
264
AUTHORS' ABSTRACTS
5 ,,~. Barna, P. B. Barna, G. Radn6czi, F. M. Reicha and L. Tbth, Phys. Status Solidi A, 55 ( 19791427. 6 P.B. Barna and F. M. Reicha, Proc. 8th Int. Vacuum Congr., Cannes, 1980. Vol. 1, p. 165. 7 P.B. Barna, ,~. Barna and Z. Patti, Acta Phys. Acad. Sci. llung., 49 (1980} 77. 8 F.M. Reicha and P. B. Barna, Acta Phys. Acad. Sci. Hung., 49 II980) 273.
263
PREPARATION AND CHARACTERIZATION
SURFACE CHEMICAL PHENOMENA AND GROWTH OF FILMS* P. B. BARNA
Research Institute for Technical Physics of the Hungarian Academy of Sciences, 1325 Budapest, P.O. Box 76 (Hungary)
To obtain an understanding of the different structures and properties of real thin films, surface chemical interactions taking place between the nascent growing film surfaces and impinging foreign species (impurities) should be considered. Active impurities have been found to influence the atom-by-atom building process of films. Surface defects on the growing films (e.g. steps, kinks and vacancies) represent the sites of film growth, i.e. sites to which new adatoms can bind, and at the same time they are the very active sites of surface chemical interactions ~. During film formation these sites are continuously produced by the growth mechanisms. Consequently, the most active initial stage of surface chemical interactions can take place during the dynamic development of films. In this paper surface chemical interactions contributing to the condensation of foreign species or to the development of new stable phases or compounds will be discussed. The crystal face anisotropy in the microchemical activity found by Martinson et al. 2 and Michel et al. 3 results in the anisotropy in crystal growth. I n s i t u experiments have shown the accumulation of foreign species by the moving growth steps onto the surfaces of growing crystals and the development of layers which cover the surfaces either partly or completely4' 2. In this way the growth and coalescence of crystals are governed by their orientation and by the development of surface-covering layers6. The surface chemical interactions taking place at the very active surface sites on the nascent film surface 7 and the accumulation of their products by the moving steps make the developing structure and its properties very sensitive to impurities, even at rather low contamination levels s. These impurities can be very active in influencing the structure and properties as well as in causing the development of structural peculiarities for which crystal face anisotropy in the microchemical activity exists. 1 G.A. Somorjai, Adv. Catal.(1977) 1. 2 3 4
C . W . B . Martinson, S. A. Flodstr6m, J. Rundgren and P. Westrin, Surf Sci., 89 (1979) 102. R. Michel, J. Castaldi, C. Allasia, C. Jourdan and J. Derrien, Surf Sci., 95 (1980) 102. J . F . P6cza, A. Barna, P. B. Barna, I. Pozsgai and G. Radn6czi, Jpn. J. Appl. Phys., Suppl. 2, Part 1 (1974) 525.
*Abstract of a paper presented at the International Summer School on Processes of Thin Film Formation, Fony6d, Lake Balaton, Hungary, September 28 to October 4, 1980. 0040-6090/81/0000-0000/S02.50
g;. Elsevier Sequoia,'Printed in The Netherlands
264
AUTHORS' ABSTRACTS
5 ,,~. Barna, P. B. Barna, G. Radn6czi, F. M. Reicha and L. Tbth, Phys. Status Solidi A, 55 ( 19791427. 6 P.B. Barna and F. M. Reicha, Proc. 8th Int. Vacuum Congr., Cannes, 1980. Vol. 1, p. 165. 7 P.B. Barna, ,~. Barna and Z. Patti, Acta Phys. Acad. Sci. llung., 49 (1980} 77. 8 F.M. Reicha and P. B. Barna, Acta Phys. Acad. Sci. Hung., 49 II980) 273.