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207. Cathode sputtering of metals using copper ions
Classified Abstracts
72
response of the untreated film occurs at a thickness of approximately 400 A. For the heat treated film (24O”C), this shifts to W. J. S. approximately 8OOA. G. Goureaux, et al., C. R. Acad. Sci. Paris, 254 (18), 30 April 1962, 3195-3197. 30 : 41 : 56 201. On the electrical resistance of thin strips of silver and the therm0 e.m.f. of a couple consisting of massive and thin silver. France. The authors have shown in a previous paper that the variation in resistance with temperature of thin strips of silver is the same as that obtained with thin layers deposited on glass or silica by thermal evaporation. Similar results have now been obtained with layers deposited on mica, provided the latter was kept at a low temperature (20-25°C) during the process of deposition. As in the case of silver on mica, epitaxial phenomena arise when the support reaches temperatures near 150°C. The present paper deals with the thermal e.m.f. generated when thin films deposited on glass or mica were combined with a thick wire of the same metal (silver) to form a thermocouple. The film ranged in thickness from 32 to 430 rnp and the e.m.f. was measured with the cold junction at 0°C and the hot ranging up to 175°C. For the same thickness of film, the e.m.f. generated at a given temperature when its base was mica was practically double than what it was for glass. In either case, however, the thermoelectric power p = dE/dt was negative. The authors give theoretical reasons for this. It should be noted that all measurements were carried out in a vacuum of 10e5 W. J. S. torr. F. Savornin, et al., C. R. Acad. Sci. Paris, 234 (19), 7 May 1962, 3348-3350. 30 : 41 : 19 202. Experimental study of the optical properties of thin layers of aluminium in the visible and near infrared. France. It is known that certain metals when in the form of thin films exhibit peculiar optical properties. A well marked absorption band appears in their case which does not correspond to a transition in their atomic state nor is shown by the metal in bulk. In the case of gold and silver, this absorption band is in the visible range of wavelenghts. The author carried out similar experiments with aluminium films ranging in thickness from 6 to 33 mp, prepared by vacuum evaporation on a quartz base. It appears that in the case of aluminium, the absorption band is much wider than in the case of gold and silver and extends over the region h = .45 to X = .55~. The author suggests that this wide band is the result of a superposition of two narrower bands, one of which corresponds to a transition of an election from the 3p band to the surface band while the other is due to the passage of an election from the w. I. s. surface band to the 4s band. J. Richard,
C. R. Acad. Sri. Paris, 255 (4), 23 July 1962, 668-670.
30 : 41 : 19 : 56 203. Photoelectric efficiency of thin films of gold. France. The films were deposited by vacuum evaporation on a base of quartz and ranged in thickness from 4 to 18 m+ Their photoelectric behaviour was examined over the range of wavelengths 302 to 244 mp. Irrespective of wavelength, maximum response was obtained for a film thickness of 4.9 resp. 6 rnp, depending on whether the absorbed or incident flux was used as a reference basis. Films thinner than 4 rnp produced no measurable photoelectric current (less than lo-l4 A). The author shows that the position of maximum response corresponds to the film thickness with the smallest exit potential. W.
R. Garron, C. R. Acad. Sci. Paris, 255 (6), 6Aug.
J. S.
1962, 1107-l 109.
201-208
30 : 43 : 19 204. Oriented organic films as a diffraction grating for soft X-rays. U.S.A. American scientists working at the Virginia Institute-of Scientific Research have succeeded in building UD oriented films of long chain behemic and lignoceric fatty acids. _From 70 up to 240 monomolecular films are superposed on a nickel surface using a technique first developed by Langmuir. The oriented film is useful as a diffraction grating for soft X-rays (25 to 1OOA wavelength). W. J. S. Anon., Chem. and Engng. News, 40 (49), 3 Dec. 1962,42. 30 : 33 205. Summation formulae in the theory of thin films. Czechoslovakia. On the basis of general summation formulae for light reflected and transmitted by a thin film, the author derives formulae for a thin dielectric film, for a thin metallic film and for a system of thin dielectric films. This resolution is based on Stokes’s principle of reversibility, which is the idea unifying the cases into one theory. In conclusion he gives the solution of a general case, dealing with light reflected and transmitted by a system of thin dielectric and metallic films. (Author) A. VaHiEek, Czech. J. Phys., B12 (l), Jan. 1962,26-34. 30 : 41 : 33 206. On the theory of ferromagnetic thin films. Rumania. The second approximation in the calculation of the partition function by the traces method of ferromagnetic thin films gives wrong results for the co-ordination number equal to eight. To obtain correct results even for this case, the third order approximation of the partition function is developed and thus the magnetic properties of body-centred cubic iron thin films are studied. The dependance of the Curie temperature on the thickness, for different values of the ratio between the anisotropy constant and the exchange energy between two neighbours, is discussed. A value can be chosen for this ratio such that the thin film becomes ferromagnetic only for a thickness greater than a definite value. (Authors, modified) A. Corciovei and G. Ghika, Czech. J. Phys., B12 (4), April 1962, 278-295. 30 : 41 207. Cathode sputtering of metals using copper ions. Czechoslovakia. Copper ions, obtained from the plasma of a lowpressure discharge burning in a hollow cathode in an argon atmosphere, were used to study cathode sputtering. A diagram and description of the discharge tube employed are given. Before measurement, the apparatus was outgassed to a pressure of lo-’ mmHg and at the same time the innerparts of theapparatus were heated to 45O”C, the temperature being measured by a thermocouple placed on the sample. Measurements were carried out on aluminium, silver, moIybdenum, nickel, tungsten, germanium and silicon samples. At an incident energy of 1000 eV it was found that a copper film remained only on Al, Ag and Ge. Film began to form on the other materials when the incident energy of the ions was reduced to below 300 eV. D. A. P. E. BiEka, Czech. J. Phys., B12 (ll), Nov. 1962, 865-867. 30 : 41 : 33 208. Static reversal processes in thin Ni-Fe films. U.S.A. Magnetization reversal at an angle to the easy direction in Ni-Fe films was studied. The results. in contrast to the singledomain theory, show no coherent rotation, even for field dicections in which the critical field for rotation is smaller than the critical field for wall motion. The actual reversal is initiated by rotation of the magnetization in bands formed in the film. New experimental studies show that the reversal is subsequently completed by wall motion. A qualitative discussion of the new observations and a review of previous work give a comprehensive picture of the static reversal processes in thin Ni-Fe films. (Author) S. Middelhoek, IBM J. Res. Developm., 6 (4), Oct. 1962, 394-406.
72
response of the untreated film occurs at a thickness of approximately 400 A. For the heat treated film (24O”C), this shifts to W. J. S. approximately 8OOA. G. Goureaux, et al., C. R. Acad. Sci. Paris, 254 (18), 30 April 1962, 3195-3197. 30 : 41 : 56 201. On the electrical resistance of thin strips of silver and the therm0 e.m.f. of a couple consisting of massive and thin silver. France. The authors have shown in a previous paper that the variation in resistance with temperature of thin strips of silver is the same as that obtained with thin layers deposited on glass or silica by thermal evaporation. Similar results have now been obtained with layers deposited on mica, provided the latter was kept at a low temperature (20-25°C) during the process of deposition. As in the case of silver on mica, epitaxial phenomena arise when the support reaches temperatures near 150°C. The present paper deals with the thermal e.m.f. generated when thin films deposited on glass or mica were combined with a thick wire of the same metal (silver) to form a thermocouple. The film ranged in thickness from 32 to 430 rnp and the e.m.f. was measured with the cold junction at 0°C and the hot ranging up to 175°C. For the same thickness of film, the e.m.f. generated at a given temperature when its base was mica was practically double than what it was for glass. In either case, however, the thermoelectric power p = dE/dt was negative. The authors give theoretical reasons for this. It should be noted that all measurements were carried out in a vacuum of 10e5 W. J. S. torr. F. Savornin, et al., C. R. Acad. Sci. Paris, 234 (19), 7 May 1962, 3348-3350. 30 : 41 : 19 202. Experimental study of the optical properties of thin layers of aluminium in the visible and near infrared. France. It is known that certain metals when in the form of thin films exhibit peculiar optical properties. A well marked absorption band appears in their case which does not correspond to a transition in their atomic state nor is shown by the metal in bulk. In the case of gold and silver, this absorption band is in the visible range of wavelenghts. The author carried out similar experiments with aluminium films ranging in thickness from 6 to 33 mp, prepared by vacuum evaporation on a quartz base. It appears that in the case of aluminium, the absorption band is much wider than in the case of gold and silver and extends over the region h = .45 to X = .55~. The author suggests that this wide band is the result of a superposition of two narrower bands, one of which corresponds to a transition of an election from the 3p band to the surface band while the other is due to the passage of an election from the w. I. s. surface band to the 4s band. J. Richard,
C. R. Acad. Sri. Paris, 255 (4), 23 July 1962, 668-670.
30 : 41 : 19 : 56 203. Photoelectric efficiency of thin films of gold. France. The films were deposited by vacuum evaporation on a base of quartz and ranged in thickness from 4 to 18 m+ Their photoelectric behaviour was examined over the range of wavelengths 302 to 244 mp. Irrespective of wavelength, maximum response was obtained for a film thickness of 4.9 resp. 6 rnp, depending on whether the absorbed or incident flux was used as a reference basis. Films thinner than 4 rnp produced no measurable photoelectric current (less than lo-l4 A). The author shows that the position of maximum response corresponds to the film thickness with the smallest exit potential. W.
R. Garron, C. R. Acad. Sci. Paris, 255 (6), 6Aug.
J. S.
1962, 1107-l 109.
201-208
30 : 43 : 19 204. Oriented organic films as a diffraction grating for soft X-rays. U.S.A. American scientists working at the Virginia Institute-of Scientific Research have succeeded in building UD oriented films of long chain behemic and lignoceric fatty acids. _From 70 up to 240 monomolecular films are superposed on a nickel surface using a technique first developed by Langmuir. The oriented film is useful as a diffraction grating for soft X-rays (25 to 1OOA wavelength). W. J. S. Anon., Chem. and Engng. News, 40 (49), 3 Dec. 1962,42. 30 : 33 205. Summation formulae in the theory of thin films. Czechoslovakia. On the basis of general summation formulae for light reflected and transmitted by a thin film, the author derives formulae for a thin dielectric film, for a thin metallic film and for a system of thin dielectric films. This resolution is based on Stokes’s principle of reversibility, which is the idea unifying the cases into one theory. In conclusion he gives the solution of a general case, dealing with light reflected and transmitted by a system of thin dielectric and metallic films. (Author) A. VaHiEek, Czech. J. Phys., B12 (l), Jan. 1962,26-34. 30 : 41 : 33 206. On the theory of ferromagnetic thin films. Rumania. The second approximation in the calculation of the partition function by the traces method of ferromagnetic thin films gives wrong results for the co-ordination number equal to eight. To obtain correct results even for this case, the third order approximation of the partition function is developed and thus the magnetic properties of body-centred cubic iron thin films are studied. The dependance of the Curie temperature on the thickness, for different values of the ratio between the anisotropy constant and the exchange energy between two neighbours, is discussed. A value can be chosen for this ratio such that the thin film becomes ferromagnetic only for a thickness greater than a definite value. (Authors, modified) A. Corciovei and G. Ghika, Czech. J. Phys., B12 (4), April 1962, 278-295. 30 : 41 207. Cathode sputtering of metals using copper ions. Czechoslovakia. Copper ions, obtained from the plasma of a lowpressure discharge burning in a hollow cathode in an argon atmosphere, were used to study cathode sputtering. A diagram and description of the discharge tube employed are given. Before measurement, the apparatus was outgassed to a pressure of lo-’ mmHg and at the same time the innerparts of theapparatus were heated to 45O”C, the temperature being measured by a thermocouple placed on the sample. Measurements were carried out on aluminium, silver, moIybdenum, nickel, tungsten, germanium and silicon samples. At an incident energy of 1000 eV it was found that a copper film remained only on Al, Ag and Ge. Film began to form on the other materials when the incident energy of the ions was reduced to below 300 eV. D. A. P. E. BiEka, Czech. J. Phys., B12 (ll), Nov. 1962, 865-867. 30 : 41 : 33 208. Static reversal processes in thin Ni-Fe films. U.S.A. Magnetization reversal at an angle to the easy direction in Ni-Fe films was studied. The results. in contrast to the singledomain theory, show no coherent rotation, even for field dicections in which the critical field for rotation is smaller than the critical field for wall motion. The actual reversal is initiated by rotation of the magnetization in bands formed in the film. New experimental studies show that the reversal is subsequently completed by wall motion. A qualitative discussion of the new observations and a review of previous work give a comprehensive picture of the static reversal processes in thin Ni-Fe films. (Author) S. Middelhoek, IBM J. Res. Developm., 6 (4), Oct. 1962, 394-406.