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Apparatus for the controlled co-deposition on MnBi thin films
Classified
abstracts
600-610
Vacuum integrity of the tube, on the system, is kept intact at all times. Preparation of a tube for opening is discussed in detail. Gases evolved due to the opening device piercing the metal tube envelope are also discussed. B I Grady, (Proc 19th Nat Symp Am Vat Sot) J Vuc Sci Tech&, 10 (l), Jan/Feb 1973, 208-211. 22 600. Measuring hydrocarbon gas pressure with an ionization gauge. (USA) The sensitivity of an ionization gauge for CH.,, CzH4, C2H6, and CaH,CH3 has been determined. Results obtained indicate an almost linear increase in sensitivity for these hydrocarbons with the number of electrons per molecule. A reduction in ionization gauge sensitivity was observed after several hours of operation in a hydrocarbon atmosphere. Results obtained here indicate the reduction in sensitivity is due to a high electrical resistance layer formation on the small wire probe ion collector of the Bayard-Alpert ionization gauge. The sensitivity can be restored by electron bombardment of the collector or operating the gauge for several hours in an O2 atmosphere near lo-“ torr. The high resistance layer buildup can be prevented for many hours by operating the gauge at 250°C. J R Young, (Proc 19th Nat Symp Am Vat Sot) J Vuc Sci Tech&, 10 (l), Jan/Feb 1973,212-214. 22 601. Thermal transpiration error in ahsolute pressure measurement with capacitance manometers. (USA) Readings of two Baratron capacitance manometers with sensors at unequal temperatures, when compared over a wide range of pressures in helium and nitrogen, demonstrate appreciable nonlinearity caused by thermal transpiration. The asymptotic indication ratio at low pressure, 1.026 f 0.002, is approximately double the value reported by Bromberg, but considerably less than the Knudsen ratio for apertures. The data can be fitted to the Liang Equation, but the coefficients are sensitive to the geometry of the apparatus in the region of temperature transition. G C Baldwin and M R Gaerttner, (Proc 19th Nat Symp Am Vat Sot) J Vat Sci Technol, 10 (l), Jan/Feb 1973,215-217. 22 602. An ultrasensitive hydrogen detector and its applications. (USA) K B Das, Abstract. (Proc 19th Nat Symp Am Vat Sot) J Vuc Sci Technol, 10 (l), Jan/Feb 1973, 175. 23. PLUMBING 23 603. A vacuum lock facility for the rauid insertion of suecimens to UHV. (GB) A vacuum lock is described which enables specimens to be transferred from atmosphere to pressures in the region of 2 x IO-* Pa without lengthy bake-out pro&dures. The designis such that standard vacuum components can be used and a minimum of accurate machining is required. V W Steward and C H A Syms, J Phys E: Scient Instrum, 6 (l), Jan 1973, 14-15. 24. VALVES 24 604. Use of stabilized zlrconia as a selective oxygen leak source. (USA) C J Mogab, Abstract. (Proc 19th Nat Symp Am Vat Sot) J Vat Sci Technol, 10 (l), Jun/Feb 1973, 291. 26. AUTOMATIC
PROTECTIVE
AND CONTROL EQUIPMENT
26 605. Pneumatic logic controls for automatic vacuum systems. (USA) High-pressure modularly mounted diaphragm air logic elements are extremely useful in vacuum systems controls, because of their versatility, easy assembly, and freedom from effects of electrical noise. Systems designers without previous logic programming experience will find these systems relatively easy to design. The elements operate on clean house air from 25 to 150 psi and therefore require no amolification. Circuit designs and assembly procedures are discussed in detail, including optimized designs successfully used at LLL. C E Hugenberger and D E Petrich, (Proc 19th Nat Symp Am Vat Sot) J Vat Sci Technol, 10 (l), Jrm/Feb 1973, 254-257.
IlLVacuum
applications
30. EVAPORATION
AND SPUTTERING
30 606. Apparatus for the controlled co-deposition of MnBi thin lilms. (GB) Equipment has been constructed for the preparation of manganese bismuth thin tilms by co-deposition in vacuum. A quartz crystal microbalance has been used to monitor the deposition of each constituent of the alloy and the composition of the alloy determined by a simple closed loop control system. Calibration of the control system in terms of the composition of the film produced has been accomplished using a supplementary quartz crystal microbalance. X-ray fluorescence analysis of 100 nm thick MnBi films shows the codeposition equipment produces alloy films with a percentage composition controllable to better than f3.5%. D King et al, JPhys E: Scient Znstrum, 6 (l), Jan 1973, 86-89. 30:33 607. Fluorescence of telraphenyl-butadiene in the vacuum nltraviolet. (GB) Tetraphenyl-butadiene is a useful alternative to sodium salicylate as a fluorescent wavelength converter for detectors in the vacuum uv. Measurements of the fluorescence efficiency of TPB relative to sodium salicylate over the wavelength range 735-3160 A are presented, and the application of TPB coatings to image tube detectors is discussed. Over the entire wavelength range studied TPB had a higher fluorescent efficiency than sodium salicylate. W M Burton and B A Powell, Appl Opt, 12 (l), Jan 1973,87-89. 30 608. Recent advances in the chemical vapour growth of electronic materials. (USA) The chemical vapour growth technique has been used extensively for the preparation and crystal growth of electronic materials either in the bulk form or as thin layers on substrate surfaces. Using the chemical transport technique or the reaction of gaseous compounds containing the constituents of the desired material, electronic materials with thicknesses in a wide range can be prepared at temperatures considerably below their melting points or decomposition temperatures. Furthermore, the impurity concentration and distribution in the product can be controlled to an extent not obtainable by other techniques. The recent progress in the chemical vapour growth of semiconductors, insulators, conductors, magnetic materials, and superconductors is discussed with emphasis on the epitaxial growth of semiconductors. T L Chu and R K Smeltzer, (Proc 19th Nat Symp Am Vat Sot) J Vuc Sci Technol, 10 (l), Jan/Feb 1973, l-10. 30 609. The growth of a GaAs-GaAlAs superlattice. (USA) An ultra high vacuum epitaxy system is described, including special features such as computer control. The system is capable of preparing sophisticated structures requiring a high degree of precise control. GaAlAs 6lms have been grown and evaluated by various techniques; He-ion backscattering and Raman spectroscopy have been shown to be particularly valuable for periodic structures. A structure with a very narrow period has been made, and its transport properties measured and interpreted by the superlattice mechanism. L L Chang et al, (Proc 19th Nat Symp Am Vat Sot) J Vat Sci Technol, 10 (l), Jun/Feb 1973, 11-16. 30 610. The preparation of thin 6hns of B-l structure superconducting ternary compounds. (USA) NbN, a binary B-l structure superconducting compound, has been successfully prepared in thin film form by a high-purity sputtering orocess IJ R Gavaler. J K Hulm. M A Janocko and C K Jones, J Vat kci Tecikol, 6, 177, i969]. In this paper, we report on the deposition of ternary compounds, based on NbN, using a similar technique. The inclusion of a third element, such as carbon, titanium, or zirconium into the NbN structure was accomplished by sputtering in an argon-nitrogen atmosphere from a two-element target. These targets were made either by hot pressing a powder mixture of the elements into a proper form or by welding together two metal sheets into a single unit. Superconducting transition temperatures of 2 17 K have been pbtained in both Nb-C-N and Nb-TiN thin films by depositing 339
abstracts
600-610
Vacuum integrity of the tube, on the system, is kept intact at all times. Preparation of a tube for opening is discussed in detail. Gases evolved due to the opening device piercing the metal tube envelope are also discussed. B I Grady, (Proc 19th Nat Symp Am Vat Sot) J Vuc Sci Tech&, 10 (l), Jan/Feb 1973, 208-211. 22 600. Measuring hydrocarbon gas pressure with an ionization gauge. (USA) The sensitivity of an ionization gauge for CH.,, CzH4, C2H6, and CaH,CH3 has been determined. Results obtained indicate an almost linear increase in sensitivity for these hydrocarbons with the number of electrons per molecule. A reduction in ionization gauge sensitivity was observed after several hours of operation in a hydrocarbon atmosphere. Results obtained here indicate the reduction in sensitivity is due to a high electrical resistance layer formation on the small wire probe ion collector of the Bayard-Alpert ionization gauge. The sensitivity can be restored by electron bombardment of the collector or operating the gauge for several hours in an O2 atmosphere near lo-“ torr. The high resistance layer buildup can be prevented for many hours by operating the gauge at 250°C. J R Young, (Proc 19th Nat Symp Am Vat Sot) J Vuc Sci Tech&, 10 (l), Jan/Feb 1973,212-214. 22 601. Thermal transpiration error in ahsolute pressure measurement with capacitance manometers. (USA) Readings of two Baratron capacitance manometers with sensors at unequal temperatures, when compared over a wide range of pressures in helium and nitrogen, demonstrate appreciable nonlinearity caused by thermal transpiration. The asymptotic indication ratio at low pressure, 1.026 f 0.002, is approximately double the value reported by Bromberg, but considerably less than the Knudsen ratio for apertures. The data can be fitted to the Liang Equation, but the coefficients are sensitive to the geometry of the apparatus in the region of temperature transition. G C Baldwin and M R Gaerttner, (Proc 19th Nat Symp Am Vat Sot) J Vat Sci Technol, 10 (l), Jan/Feb 1973,215-217. 22 602. An ultrasensitive hydrogen detector and its applications. (USA) K B Das, Abstract. (Proc 19th Nat Symp Am Vat Sot) J Vuc Sci Technol, 10 (l), Jan/Feb 1973, 175. 23. PLUMBING 23 603. A vacuum lock facility for the rauid insertion of suecimens to UHV. (GB) A vacuum lock is described which enables specimens to be transferred from atmosphere to pressures in the region of 2 x IO-* Pa without lengthy bake-out pro&dures. The designis such that standard vacuum components can be used and a minimum of accurate machining is required. V W Steward and C H A Syms, J Phys E: Scient Instrum, 6 (l), Jan 1973, 14-15. 24. VALVES 24 604. Use of stabilized zlrconia as a selective oxygen leak source. (USA) C J Mogab, Abstract. (Proc 19th Nat Symp Am Vat Sot) J Vat Sci Technol, 10 (l), Jun/Feb 1973, 291. 26. AUTOMATIC
PROTECTIVE
AND CONTROL EQUIPMENT
26 605. Pneumatic logic controls for automatic vacuum systems. (USA) High-pressure modularly mounted diaphragm air logic elements are extremely useful in vacuum systems controls, because of their versatility, easy assembly, and freedom from effects of electrical noise. Systems designers without previous logic programming experience will find these systems relatively easy to design. The elements operate on clean house air from 25 to 150 psi and therefore require no amolification. Circuit designs and assembly procedures are discussed in detail, including optimized designs successfully used at LLL. C E Hugenberger and D E Petrich, (Proc 19th Nat Symp Am Vat Sot) J Vat Sci Technol, 10 (l), Jrm/Feb 1973, 254-257.
IlLVacuum
applications
30. EVAPORATION
AND SPUTTERING
30 606. Apparatus for the controlled co-deposition of MnBi thin lilms. (GB) Equipment has been constructed for the preparation of manganese bismuth thin tilms by co-deposition in vacuum. A quartz crystal microbalance has been used to monitor the deposition of each constituent of the alloy and the composition of the alloy determined by a simple closed loop control system. Calibration of the control system in terms of the composition of the film produced has been accomplished using a supplementary quartz crystal microbalance. X-ray fluorescence analysis of 100 nm thick MnBi films shows the codeposition equipment produces alloy films with a percentage composition controllable to better than f3.5%. D King et al, JPhys E: Scient Znstrum, 6 (l), Jan 1973, 86-89. 30:33 607. Fluorescence of telraphenyl-butadiene in the vacuum nltraviolet. (GB) Tetraphenyl-butadiene is a useful alternative to sodium salicylate as a fluorescent wavelength converter for detectors in the vacuum uv. Measurements of the fluorescence efficiency of TPB relative to sodium salicylate over the wavelength range 735-3160 A are presented, and the application of TPB coatings to image tube detectors is discussed. Over the entire wavelength range studied TPB had a higher fluorescent efficiency than sodium salicylate. W M Burton and B A Powell, Appl Opt, 12 (l), Jan 1973,87-89. 30 608. Recent advances in the chemical vapour growth of electronic materials. (USA) The chemical vapour growth technique has been used extensively for the preparation and crystal growth of electronic materials either in the bulk form or as thin layers on substrate surfaces. Using the chemical transport technique or the reaction of gaseous compounds containing the constituents of the desired material, electronic materials with thicknesses in a wide range can be prepared at temperatures considerably below their melting points or decomposition temperatures. Furthermore, the impurity concentration and distribution in the product can be controlled to an extent not obtainable by other techniques. The recent progress in the chemical vapour growth of semiconductors, insulators, conductors, magnetic materials, and superconductors is discussed with emphasis on the epitaxial growth of semiconductors. T L Chu and R K Smeltzer, (Proc 19th Nat Symp Am Vat Sot) J Vuc Sci Technol, 10 (l), Jan/Feb 1973, l-10. 30 609. The growth of a GaAs-GaAlAs superlattice. (USA) An ultra high vacuum epitaxy system is described, including special features such as computer control. The system is capable of preparing sophisticated structures requiring a high degree of precise control. GaAlAs 6lms have been grown and evaluated by various techniques; He-ion backscattering and Raman spectroscopy have been shown to be particularly valuable for periodic structures. A structure with a very narrow period has been made, and its transport properties measured and interpreted by the superlattice mechanism. L L Chang et al, (Proc 19th Nat Symp Am Vat Sot) J Vat Sci Technol, 10 (l), Jun/Feb 1973, 11-16. 30 610. The preparation of thin 6hns of B-l structure superconducting ternary compounds. (USA) NbN, a binary B-l structure superconducting compound, has been successfully prepared in thin film form by a high-purity sputtering orocess IJ R Gavaler. J K Hulm. M A Janocko and C K Jones, J Vat kci Tecikol, 6, 177, i969]. In this paper, we report on the deposition of ternary compounds, based on NbN, using a similar technique. The inclusion of a third element, such as carbon, titanium, or zirconium into the NbN structure was accomplished by sputtering in an argon-nitrogen atmosphere from a two-element target. These targets were made either by hot pressing a powder mixture of the elements into a proper form or by welding together two metal sheets into a single unit. Superconducting transition temperatures of 2 17 K have been pbtained in both Nb-C-N and Nb-TiN thin films by depositing 339