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1120. Classification of photoemission films
Classified abstracts 1110--1121 24 1110. Method of admitting hydrogen to a vacuum system. (USSR) A simplified method of introducing hydrogen into a vacuum system without any danger of explosions is described. The principle of the method is based on the penetration of atomic hydrogen released by the electrolysis of water through palladium and palladium alloys. The mechanism of the electrolysis is such as to ensure a steady flow of hydrogen through the metal, even at room temperatures. By varying the rate of electrolysis with the help of a conventional rheostat, a wide range of variation of the rate of hydrogen admission may be achieved. The relatively low working temperature prevents the penetration of undesirable impurities into the vacuum space at the same time as the hydrogen. Yu A Balovnev, USSR Patent, No 276,267, appl 5th May 1969, publd 22nd Oct 1970. 24 1111. High-speed gas valve. (USSR) Construction of a valve for the introduction of gas at high speed into gas-filled chambers used in gas-discharge, plasma and gas-dynamic experiments is presented. Opening times of 0.5 to 2/~sec are achieved by utilizing a plasma stream to destroy a metallic or organic foil. N F Vladimirov et al, Prib Tekh Eksper, No 1, 1971, 177-179 (in
Russian). 24 1112. Two constructions of load lock arrangements for industrial high vacuum evaporators. (USSR) The results of investigation of load lock arrangements showed that the principal factor in the design of such systems was the choice of parameters of the first stage where with different combinations of pumping speeds and dimensions of diffusion inlets the pressure varies over broad limits. If in the first stage a pressure of 1 to 10 tort is maintained then the choice of parameters of the second stage is an easy task. For systems reaching a pressure of 10-6 torr in the working chamber, a two-stage lock arrangement with mechanical pumps in both stages is sufficient in most cases. Application of high vacuum pumps in the second stage is not advantageous. A load lock arrangement with a sliding loading cylinder is suitable for thermal evaporation systems with high speed of operation. Lock arrangements for continuous loading and unloading guarantee high overall productivity. A A Trunin et al, Elektron Tekh Mikroelektron, 3, 1970, 129-135 (in
Russian). 24 1113. Introduction of water vapour into vacuum systems and the adsorption by the walls. (USA) A technique described whereby precise amounts of water vapour can be introduced into evacuated glass-Kovar stainless steel systems. The adsorption of water vapour by the walls of a typical vacuum system maintained at 26.8°C is reported in the range 0.03~).20 relative pressure. A continuous dynamic behaviour was observed over time intervals up to 4000 min, where time zero corresponds to the initial contact of the walls with the water vapour. V R Deitz and N H Turner, J Vac Sci Technol, 7 (6), Nov/Dec 1970, 577-580. 25. BAFFLES, TRAPS AND REFRIGERATION E Q U I P M E N T 25 1114. A priming vacuum trap. (USSR) A vacuum trap incorporating a special device for maintaining a constant level of liquid nitrogen in the trap during the operation of the associated vacuum system is described. The reservoir of this trap contains a cylinder closed at one end, the open end facing the bottom of the reservoir. The upper (closed) end contains an aperture communicating with the aperture in the reservoir through which the coolant is poured. When the level of liquid nitrogen reaches a specified point in the cylinder, the air between the cylinder and the reservoir proper forms a detached "air cushion" which holds the working level of the nitrogen in one particular position. Tests confirm the reliable operation of this device. M N Blinov, USSR Patent, No 275,287, appl 3rdApri11969, publd 13th Oct 1970. 25 1115. Nitrogen-free cryostats for liquid helium with high-vacuum insulation. (USSR) Cryostats for liquid helium without additional cooling of radiation shields by liquid nitrogen have been developed and examined. The
cryostats have liquid helium tank volumes of 0.25 × 10-3 to 1 x 10 -a m 8 and maintain the working temperature for 10 to 22 hours. N A Pankratov and V S Golubkov, Elektron Tekh Kriogen Elektron, 1, 1970, 72-80 (in Russian). 25 1116. Miniature equipment for liquid nitrogen manufacture. (USSR) A miniature system for obtaining liquid nitrogen from air without preliminary compression is described. A K Digoev, Elektron Tekh Gazorazryad Prib, 3, 1970, 124-125 (in
Russian). 28. HEATING E Q U I P M E N T AND T H E R M O M E T E R S 28 1117. Method of measuring and regulating temperature. (USSR) An improved method of measuring and regulating the temperature of the heating elements in the manufacture of radio valves is described. The process is simplified by dividing the current passing through the heater into two branches (measuring and regulating), one half wave passing through each. Thus the measuring half wave gives a signal representing the resistance and hence the temperature of the system, while the other half wave regulates the amount of power fed to the heater in accordance with the signal from the first half wave. Separation is achieved by means of two simple diodes. In this way the temperature may be regulated and recorded automatically at the same time. A A Romanov et al, USSR Patent, No 273,550, appl 7th May 1968, publd lOth Sept 1970.
III. Vacuum applications 30. EVAPORATION AND SPUTTERING 30 1118. Apparatus for vacuum-depositing coatings. (USSR) Improvements to existing systems for the vacuum-deposition of thin coatings are described. Thus, whereas existing continuous filmdeposition installations are made in the form of a series of simple drums for cleaning the surface and cooling and coating the parts under treatment, the improved version incorporates a composite drum made in two sections, the shape and configuration of this being specially designed to improve continuity of operation and make working conditions easier. A Ya Vigant et al, USSR Patent, No 273,617, appl 1st July 1968, publd 8th Sept 1970. 30 1119. Device for the vacuum-evaporation of metals. (USSR) An improvement to the normal type of vacuum-evaporation apparatus incorporating a thermal evaporator, a bunker, and a transporting system is described. The new version is distinguished in that it includes a bunker in the form of a sector, containing a number of grooves, while the transporting system incorporates a more efficient clamping device. The improved evaporator facilitates the simultaneous evaporation of several samples from a single evaporator. V D Golemenkov and A N Zhdanov, USSR Patent, No 256,459, appl 17th Nov 1969,publd 31st Aug 1970. 30 1120. Classification of photoemission films. (Germany) Films used as efficient photoemitters in vacuum are classified on a basis of chemical composition, type of chemical bond, structure of crystal lattice and type of electrical conductivity. The application of photoelectron emission as a tool for investigation of the band structure of materials is discussed. P Gorlich and K Sumi, Experim Techn Phys, 17 (3), 1969, 193-203 (in
German). 3O 1121. Nucleation of epitaxiai films by gas-transport technique. (Germany) The nucleation and the subsequent growth of gallium arsenide films in iodide and chloride processes were studied by replica, transmission electron microscopy and X-ray analysis. The deposition was performed on GaAs substrates with different orientations. In the case of GaAs hetero-epitaxy, substrates of (111) Ge and Si were used. In all cases, three-dimensional nuclei were observed in the initial stages of the film formation. Their number and size increased with time. The nuclei grew, merged, and formed a continuous film, the surface of which became smooth. On the smooth surface three-dimensional 497
Russian). 24 1112. Two constructions of load lock arrangements for industrial high vacuum evaporators. (USSR) The results of investigation of load lock arrangements showed that the principal factor in the design of such systems was the choice of parameters of the first stage where with different combinations of pumping speeds and dimensions of diffusion inlets the pressure varies over broad limits. If in the first stage a pressure of 1 to 10 tort is maintained then the choice of parameters of the second stage is an easy task. For systems reaching a pressure of 10-6 torr in the working chamber, a two-stage lock arrangement with mechanical pumps in both stages is sufficient in most cases. Application of high vacuum pumps in the second stage is not advantageous. A load lock arrangement with a sliding loading cylinder is suitable for thermal evaporation systems with high speed of operation. Lock arrangements for continuous loading and unloading guarantee high overall productivity. A A Trunin et al, Elektron Tekh Mikroelektron, 3, 1970, 129-135 (in
Russian). 24 1113. Introduction of water vapour into vacuum systems and the adsorption by the walls. (USA) A technique described whereby precise amounts of water vapour can be introduced into evacuated glass-Kovar stainless steel systems. The adsorption of water vapour by the walls of a typical vacuum system maintained at 26.8°C is reported in the range 0.03~).20 relative pressure. A continuous dynamic behaviour was observed over time intervals up to 4000 min, where time zero corresponds to the initial contact of the walls with the water vapour. V R Deitz and N H Turner, J Vac Sci Technol, 7 (6), Nov/Dec 1970, 577-580. 25. BAFFLES, TRAPS AND REFRIGERATION E Q U I P M E N T 25 1114. A priming vacuum trap. (USSR) A vacuum trap incorporating a special device for maintaining a constant level of liquid nitrogen in the trap during the operation of the associated vacuum system is described. The reservoir of this trap contains a cylinder closed at one end, the open end facing the bottom of the reservoir. The upper (closed) end contains an aperture communicating with the aperture in the reservoir through which the coolant is poured. When the level of liquid nitrogen reaches a specified point in the cylinder, the air between the cylinder and the reservoir proper forms a detached "air cushion" which holds the working level of the nitrogen in one particular position. Tests confirm the reliable operation of this device. M N Blinov, USSR Patent, No 275,287, appl 3rdApri11969, publd 13th Oct 1970. 25 1115. Nitrogen-free cryostats for liquid helium with high-vacuum insulation. (USSR) Cryostats for liquid helium without additional cooling of radiation shields by liquid nitrogen have been developed and examined. The
cryostats have liquid helium tank volumes of 0.25 × 10-3 to 1 x 10 -a m 8 and maintain the working temperature for 10 to 22 hours. N A Pankratov and V S Golubkov, Elektron Tekh Kriogen Elektron, 1, 1970, 72-80 (in Russian). 25 1116. Miniature equipment for liquid nitrogen manufacture. (USSR) A miniature system for obtaining liquid nitrogen from air without preliminary compression is described. A K Digoev, Elektron Tekh Gazorazryad Prib, 3, 1970, 124-125 (in
Russian). 28. HEATING E Q U I P M E N T AND T H E R M O M E T E R S 28 1117. Method of measuring and regulating temperature. (USSR) An improved method of measuring and regulating the temperature of the heating elements in the manufacture of radio valves is described. The process is simplified by dividing the current passing through the heater into two branches (measuring and regulating), one half wave passing through each. Thus the measuring half wave gives a signal representing the resistance and hence the temperature of the system, while the other half wave regulates the amount of power fed to the heater in accordance with the signal from the first half wave. Separation is achieved by means of two simple diodes. In this way the temperature may be regulated and recorded automatically at the same time. A A Romanov et al, USSR Patent, No 273,550, appl 7th May 1968, publd lOth Sept 1970.
III. Vacuum applications 30. EVAPORATION AND SPUTTERING 30 1118. Apparatus for vacuum-depositing coatings. (USSR) Improvements to existing systems for the vacuum-deposition of thin coatings are described. Thus, whereas existing continuous filmdeposition installations are made in the form of a series of simple drums for cleaning the surface and cooling and coating the parts under treatment, the improved version incorporates a composite drum made in two sections, the shape and configuration of this being specially designed to improve continuity of operation and make working conditions easier. A Ya Vigant et al, USSR Patent, No 273,617, appl 1st July 1968, publd 8th Sept 1970. 30 1119. Device for the vacuum-evaporation of metals. (USSR) An improvement to the normal type of vacuum-evaporation apparatus incorporating a thermal evaporator, a bunker, and a transporting system is described. The new version is distinguished in that it includes a bunker in the form of a sector, containing a number of grooves, while the transporting system incorporates a more efficient clamping device. The improved evaporator facilitates the simultaneous evaporation of several samples from a single evaporator. V D Golemenkov and A N Zhdanov, USSR Patent, No 256,459, appl 17th Nov 1969,publd 31st Aug 1970. 30 1120. Classification of photoemission films. (Germany) Films used as efficient photoemitters in vacuum are classified on a basis of chemical composition, type of chemical bond, structure of crystal lattice and type of electrical conductivity. The application of photoelectron emission as a tool for investigation of the band structure of materials is discussed. P Gorlich and K Sumi, Experim Techn Phys, 17 (3), 1969, 193-203 (in
German). 3O 1121. Nucleation of epitaxiai films by gas-transport technique. (Germany) The nucleation and the subsequent growth of gallium arsenide films in iodide and chloride processes were studied by replica, transmission electron microscopy and X-ray analysis. The deposition was performed on GaAs substrates with different orientations. In the case of GaAs hetero-epitaxy, substrates of (111) Ge and Si were used. In all cases, three-dimensional nuclei were observed in the initial stages of the film formation. Their number and size increased with time. The nuclei grew, merged, and formed a continuous film, the surface of which became smooth. On the smooth surface three-dimensional 497