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Semiconducting behaviour in Bi60Sb40 alloy thin films. (GB)
Classified 24.
LEAK
abstracts
4672-4681
DETECTORS
AND
LEAK
DETECTION 24
4672. Detecting leaks in small parts. (West Germany) A report on two new leak detection processes is made. These processes are particularly suited for leak tests on smaller parts. For the first processes a modified halogen leak detector suited for parts under overpressure is described. With the help of a current of carrier gas at the test object an integral tightness test can be carried out in a few seconds. In addition, a report is given on measurements taken on a He leak detector with turbomolecular pump according to the counter flow principle. How a user can construct such a system with standard construction components is shown. This system distinguishes itself through fast operational readiness and the fact that additional cooling media such as liquid nitrogen are not necessary. H Mennenga, Vokuum Technik, 29 (7), 1980. 195-201 (in German). 24 4673. The effect of the cold water pressure test on the leakage detection with test gases on a test heat exchanger. (West Germany) To clear up the question of whether the gas leakage test should be carried out before or after the pressure testing with water, the leak rates were determined before the pressure test with all the customary leak detection processes on a test heat exchanger with graduated leaks at the points where the tubes had been rolled in. The leak rates were then determined again after the pressure test. Since it was found that. because of remaining moisture in the crevices, leaks could no longer be detected even by the most sensitive methods, drying processes of differing eNectiveness were used, each of which was followed by determining the leak rates. The results of these tests are reported and recommendations are given for the procedure to be adopted in gas leakage testing. K 0 Cavalar, Vakuum Technik, 29 (7). 1980, 201-205 (in German). 24 4674. A new simple universal leak-detector with air-cooled turbo-pump. (West Germany) A model ofa Helium-Leakdetector for universal application is shown. It is based on the experiences with a uhv-System of a large modern particleaccelerator. The main components of the system are an air-cooled turbomolecular-pump and a helium mass-spectrometer, which can also be used independently. The design is simple, the controls and the service are reduced IO a minimum. Special vacuum-characteristics ofthe turbo-pump allow for adaptation to dilferent pressure-conditions in the sample. Figures are given for different operating conditions. Clrr Falland, Vakuum Technik, 29 (7). 1980, 205-209 (in German).
III. Vacuum 30. EVAPORATION
applications AND
DEPOSITION
4675. Use of surface plasma waves for optical constants of thin metallic films. The surface plasma wave technique for E(W) and the thickness d of a metal film is discussed. Two sets of solutions can comparing d determined at another solution can be determined. W P Clren and J M Chen, J Opr Sot
IN
VACUO
30 determination of the thickness and (UDA) determining the dielectric constant without a preset expression for E(W) be derived at a given frequency. By frequency, the correct E(W) and d Am, 71 (2).
1981,
189-191.
30 4676. An optical thin film thickness monitor. (GB) A modified technique for optical monitoring of the quarter-wave stacks of dielectric materials, utilising the principle of wavelength modulation and phase sensitive detection, is suggested. The accuracy and the sensitivity of the method is very high and can be used for making the coating process self-controlled and programmable. (India) V T Cbitnis and P N Puntambekar, Vacuum, 31 (2). 1981, 113-I 15. 30 4677. Thickness dependence of resistivity in In-Bi thin films. (GB) The resistivity and temperature coefficient of resistance of vacuum deposited thin films of InBi and In,Bi of different thicknesses have been measured after annealing. The resistance measurements have also been carried out in situ during the growth of the films as the thickness increases. It is observed that annealed films behave differently from the continuously monitored growing films in their thickness dependence of resistance. The
annealed films exhibit oscillatory variation of resistance with thickness while the continuously growing films exhibit, after an initial increase. a normal continuous decrease with thickness. The oscillatory behaviour in annealed films is attributed IO quantum size effect. The absence of oscillatory behaviour in the growing films is attributed IO the defectstructure of the films. (India) V Damodara Das and M S Jagadeesh, Vac~rum, 31 (I), 1981. 15-l 7. 30 4678. Semiconducting behaviour in Bi,,Sh,, alloy thin films. (GB) Electrical resistance measurements of annealed Bl,$b,, alloy thin films of various thicknesses vacuum deposited at diNerent substrate temperatures have been carried out from about 80 K to 500 K. The observed variation in resistance with temperature has been explained on the basis of impurity conduction, band to band transition, grain boundary barrier activation of carriers and metallic behaviour in different regions of temperature. The larger band gap values observed compared to bulk are attributed to the quantum size effect and high dislocation density. The decrease in the grain boundary barrier activation energy with increasing thickness and substrate temperature has been explained on the basis of Slater’s model. (India) V Damodara Das and M S Jagadeesh, Vacuum. 31 (2). 1981, 75-77. 30 4679. Controlled growth of arsenic trisulphide films for coupling integrated optical devices (GB) The optical properties of evaporated films of arsenic trisulphide are examined in some detail and compared with bulk properties. It is proposed to use the films as a means of interconnecting integrated optical devices in high and low index materials and also for the coupling of sandwich ribbon fibres IO optical waveguides in lithium niobate. To be eNective. the films must be formed with a high degree of precision and control of film thickness and index to better than 0.01 pm and 0.01. respectively, is obtained. Stability of the films under illumination is also discussed. G Stewart et al, J Phg D: Appl Phys, 14 (2). 1981, 323-331. 30 4680. Substrate thickness considerations in electron beam lithography. (USA) A comprehensive theoretical and experimental study of the spatial distribution of electron energy dissipation in a very thin polymer film for dot, line, and parallel line exposures over a wide range of substrate thickness and exposure dosage is reported. The two Monte Carlo models used in the theoretical calculations are reviewed and the theoretical results obtained are discussed. Experimental fabrication of thin substrates and eNective techniques of electron beam lithography on such substrates are described. The concept ofequienergy dissipation contours is discussed and then used to compare experimental data with theory. Good agreement between experiment and theory has been obtained. With substrate thickness as a variable, the fundamental influence of electron scattering on the resolution of electron beam lithography has been verified. I Adesida and T E Everhart, J Appl Phys, 51 (11). 1980, 59946005. 30 4681. Versatile computer programme for absorbing optical thin film systems. (USA) The programme for the synthesis ofnonabsorbing thin film systems by the method of gradual evolution fJ. A. Dobrowolski. APPI. Optics 4. 937 (1965)] has been extended to include new features and tb’handle absorbing materials. In the analysis mode the new programme calculates the spectral transmittance, reflectance, and absorptance of any absorbing multilayer system for any angle of incidence or plane polarization. The CIE chromaticity coordinates of the coating can also be calculated. Information on the stability of the system is obtained from an automatically repeated analysis with randomly perturbed values of the construction parameters. As in the original programme the synthesis mode does not presuppose a starting design; a layer system consisting of real absorbing or nonabsorbing coating materials may be gradually evolved. The evolution and refinement are governed by the value of a merit function defined specially for each problem. In the new programme it is possible to control the sensitivity of the system performance IO changes in the construction parameters. The monitoring information mode yields data useful for the construction of a multilayer. The construction parameter determination mode deduces the actual parameters from the measured performances of the system. The operation of the programme is illustrated by examples. (Canada) J A Dobrowolski, Appl Oprics, 20 (I), 1981, 74-81. 273
LEAK
abstracts
4672-4681
DETECTORS
AND
LEAK
DETECTION 24
4672. Detecting leaks in small parts. (West Germany) A report on two new leak detection processes is made. These processes are particularly suited for leak tests on smaller parts. For the first processes a modified halogen leak detector suited for parts under overpressure is described. With the help of a current of carrier gas at the test object an integral tightness test can be carried out in a few seconds. In addition, a report is given on measurements taken on a He leak detector with turbomolecular pump according to the counter flow principle. How a user can construct such a system with standard construction components is shown. This system distinguishes itself through fast operational readiness and the fact that additional cooling media such as liquid nitrogen are not necessary. H Mennenga, Vokuum Technik, 29 (7), 1980. 195-201 (in German). 24 4673. The effect of the cold water pressure test on the leakage detection with test gases on a test heat exchanger. (West Germany) To clear up the question of whether the gas leakage test should be carried out before or after the pressure testing with water, the leak rates were determined before the pressure test with all the customary leak detection processes on a test heat exchanger with graduated leaks at the points where the tubes had been rolled in. The leak rates were then determined again after the pressure test. Since it was found that. because of remaining moisture in the crevices, leaks could no longer be detected even by the most sensitive methods, drying processes of differing eNectiveness were used, each of which was followed by determining the leak rates. The results of these tests are reported and recommendations are given for the procedure to be adopted in gas leakage testing. K 0 Cavalar, Vakuum Technik, 29 (7). 1980, 201-205 (in German). 24 4674. A new simple universal leak-detector with air-cooled turbo-pump. (West Germany) A model ofa Helium-Leakdetector for universal application is shown. It is based on the experiences with a uhv-System of a large modern particleaccelerator. The main components of the system are an air-cooled turbomolecular-pump and a helium mass-spectrometer, which can also be used independently. The design is simple, the controls and the service are reduced IO a minimum. Special vacuum-characteristics ofthe turbo-pump allow for adaptation to dilferent pressure-conditions in the sample. Figures are given for different operating conditions. Clrr Falland, Vakuum Technik, 29 (7). 1980, 205-209 (in German).
III. Vacuum 30. EVAPORATION
applications AND
DEPOSITION
4675. Use of surface plasma waves for optical constants of thin metallic films. The surface plasma wave technique for E(W) and the thickness d of a metal film is discussed. Two sets of solutions can comparing d determined at another solution can be determined. W P Clren and J M Chen, J Opr Sot
IN
VACUO
30 determination of the thickness and (UDA) determining the dielectric constant without a preset expression for E(W) be derived at a given frequency. By frequency, the correct E(W) and d Am, 71 (2).
1981,
189-191.
30 4676. An optical thin film thickness monitor. (GB) A modified technique for optical monitoring of the quarter-wave stacks of dielectric materials, utilising the principle of wavelength modulation and phase sensitive detection, is suggested. The accuracy and the sensitivity of the method is very high and can be used for making the coating process self-controlled and programmable. (India) V T Cbitnis and P N Puntambekar, Vacuum, 31 (2). 1981, 113-I 15. 30 4677. Thickness dependence of resistivity in In-Bi thin films. (GB) The resistivity and temperature coefficient of resistance of vacuum deposited thin films of InBi and In,Bi of different thicknesses have been measured after annealing. The resistance measurements have also been carried out in situ during the growth of the films as the thickness increases. It is observed that annealed films behave differently from the continuously monitored growing films in their thickness dependence of resistance. The
annealed films exhibit oscillatory variation of resistance with thickness while the continuously growing films exhibit, after an initial increase. a normal continuous decrease with thickness. The oscillatory behaviour in annealed films is attributed IO quantum size effect. The absence of oscillatory behaviour in the growing films is attributed IO the defectstructure of the films. (India) V Damodara Das and M S Jagadeesh, Vac~rum, 31 (I), 1981. 15-l 7. 30 4678. Semiconducting behaviour in Bi,,Sh,, alloy thin films. (GB) Electrical resistance measurements of annealed Bl,$b,, alloy thin films of various thicknesses vacuum deposited at diNerent substrate temperatures have been carried out from about 80 K to 500 K. The observed variation in resistance with temperature has been explained on the basis of impurity conduction, band to band transition, grain boundary barrier activation of carriers and metallic behaviour in different regions of temperature. The larger band gap values observed compared to bulk are attributed to the quantum size effect and high dislocation density. The decrease in the grain boundary barrier activation energy with increasing thickness and substrate temperature has been explained on the basis of Slater’s model. (India) V Damodara Das and M S Jagadeesh, Vacuum. 31 (2). 1981, 75-77. 30 4679. Controlled growth of arsenic trisulphide films for coupling integrated optical devices (GB) The optical properties of evaporated films of arsenic trisulphide are examined in some detail and compared with bulk properties. It is proposed to use the films as a means of interconnecting integrated optical devices in high and low index materials and also for the coupling of sandwich ribbon fibres IO optical waveguides in lithium niobate. To be eNective. the films must be formed with a high degree of precision and control of film thickness and index to better than 0.01 pm and 0.01. respectively, is obtained. Stability of the films under illumination is also discussed. G Stewart et al, J Phg D: Appl Phys, 14 (2). 1981, 323-331. 30 4680. Substrate thickness considerations in electron beam lithography. (USA) A comprehensive theoretical and experimental study of the spatial distribution of electron energy dissipation in a very thin polymer film for dot, line, and parallel line exposures over a wide range of substrate thickness and exposure dosage is reported. The two Monte Carlo models used in the theoretical calculations are reviewed and the theoretical results obtained are discussed. Experimental fabrication of thin substrates and eNective techniques of electron beam lithography on such substrates are described. The concept ofequienergy dissipation contours is discussed and then used to compare experimental data with theory. Good agreement between experiment and theory has been obtained. With substrate thickness as a variable, the fundamental influence of electron scattering on the resolution of electron beam lithography has been verified. I Adesida and T E Everhart, J Appl Phys, 51 (11). 1980, 59946005. 30 4681. Versatile computer programme for absorbing optical thin film systems. (USA) The programme for the synthesis ofnonabsorbing thin film systems by the method of gradual evolution fJ. A. Dobrowolski. APPI. Optics 4. 937 (1965)] has been extended to include new features and tb’handle absorbing materials. In the analysis mode the new programme calculates the spectral transmittance, reflectance, and absorptance of any absorbing multilayer system for any angle of incidence or plane polarization. The CIE chromaticity coordinates of the coating can also be calculated. Information on the stability of the system is obtained from an automatically repeated analysis with randomly perturbed values of the construction parameters. As in the original programme the synthesis mode does not presuppose a starting design; a layer system consisting of real absorbing or nonabsorbing coating materials may be gradually evolved. The evolution and refinement are governed by the value of a merit function defined specially for each problem. In the new programme it is possible to control the sensitivity of the system performance IO changes in the construction parameters. The monitoring information mode yields data useful for the construction of a multilayer. The construction parameter determination mode deduces the actual parameters from the measured performances of the system. The operation of the programme is illustrated by examples. (Canada) J A Dobrowolski, Appl Oprics, 20 (I), 1981, 74-81. 273