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1053. Copper contamination during the vapour epitaxial growth of GaAs
Classified abstracts 1051-1063 vapour pressure of 250 torr, is investigated with the aid of surface etching and microfractography. S Mutze and W Gloede, Exper Tech Phys, 19 (5), 1971, 413-419 (in
German). 30 1051. Device for measuring rates of evaporation in vaeuo. (USSR) A device for measuring rates of evaporation in vacuo of particular value in connection with the deposition of thin metal films is described. Thermo-sensitive elements are placed at different distances from the evaporator and the differences between their readings are recorded. These elements may be simple thermocouples; the energy of the evaporating particles which strike the thermocouples is converted into heat and the latter produces an emf proportional to the amount of matter deposited. The effect of extraneous factors such as radiation on the thermocouples may be compensated, for example, by supplying a small dc current from an external source. The meter recording the emf of the thermocouples may be graduated to read directly in evaporation rates. Yu S Rodichev and Sh A Furman, USSR Patent No 310954, appl lOth Sept 1969, publd 1st Oct 1971. 3O 1052. Electron tunnelling into amorphous InSb and GaSb films. (Germany) The tunnelling of electrons into amorphous InSb and GaSb films has been studied at different temperatures. The tunnel junctions AI-AI~O3-amorphous semiconductor-metal electrode were prepared by evaporation of thin films in a vacuum of 10-e to 10-5 torr. Doping by coevaporation has virtually no influence on the tunnelling characteristics. Diffusion of Cu and Au into the amorphous layer, however, gives a strong increase of the tunelling conductance. C Konak and J Stuke, Phys Stat Sol (a), 9 (1), Jan 1972, 333-341. 30 1053. Copper contamination during the vapour epitaxial growth of GaAs. (Germany) It is shown by photoluminescence measurements that a copper contamination may occur during the vapour epitaxiai growth of GaAs. This contamination occurs both in the epitaxial film and in the substrate. The presence of a level at 0.20 eV above the top of the valence band is introduced in n + doped material, and the corresponding acceptor centre is attributed to a Cuaa-donor complex. (France) E Fabre, Phys Stat Sol (a), 9 (1), Jan 1972, 259-262. 30 1054. A screening device. (USSR) A screening device for use in vacuum systems in connection with the deposition of thin metal films is described. The device consists of a series of lobes set in a circle and rotated by means of a flexible system of springs actuated by a hydraulic cylinder. A special seal is incorporated to prevent loss of vacuum when the screen system is set in motion. Motion is initiated by means of a simple system of levers and springs. One cylinder is provided for the forward motion of the screen and another for returning it to its original position. A A Gordeev et al, USSR Patent No 309980, appl 8th Oct 1969, publd 7th Sept 1971. 30 1055. A vacuum-deposition apparatus with an electron-bcam evaporator. (USSR) A vacuum-deposition apparatus with an electron-beam evaporator for depositing thin metal and semiconducting films is described. The epitaxial growth of germanium films is the principal application. The apparatus comprises an electron gun, together with focusing and deflecting systems and a magnetic prism; the latter serves to rotate the electron beam through 90 ° so as to prevent the accumulation of deposits on the gun itself. As a result of this and other precautions, the evaporator is capable of working reliably for 50 h or more, the chief limiting feature being the life of the gun cathode. The rate of germanium deposition is up to 2 #m/min. Yu P Terent'ev et al, Electronics Industry Scientific-Technical Collection, No 3 (1971), 62, (in Russian). 30 1056. Apparatus for the vacuum deposition of semiconducting-compound films. (USSR) An improved form of apparatus for the vacuum deposition of semiconducting films to be used in electronic devices is described. Unsuitable combinations of temperature and geometry in existing forms of apparatus frequently produce films of non-stoichiometric composition. In the new system the geometry of the principal parts and the
thermal conditions are optimized so as to ensure that the film material shall be deposited from a gas-dynamic flow with a slight super-saturation of the vapour, the material being intensively reevaporated from the substrate and the sides of the vacuum chamber. For example, in the case of CdTe the length/diameter ratio of the chamber should be equal to unity and the temperature gradient 30°C/cm. By using this apparatus stoichiometric films may be repeatedly produced, their principal parameters varying by no more than 20 per cent. Yu Z Bubnov et al, USSR Patent No 309416, appl 17th Feb 1970, publd llth Aug 1971. 30 1057. An evaporation system for vacuum installations. (USSR) An evaporation system for depositing thin metal and other films in electrical vacuum apparatus is described. In contrast to existing devices of this kind, the one here proposed incorporates an elastic electrically-insulating membrane fixed to the current leads, the latter thus being able to move (within certain limits). The operation of the system is more reliable than that of its predecessors. Apart from this, the system contains the usual heating element, evaporation unit, and electrical supplies. The elastic membrane forms the boundary between the evacuated space of the vacuum chamber and the atmosphere. A N Zhanda et al, USSR Patent No 309071, appl 22nd Dec 1969, publd7th Oct 1971. 31. EVACUATION AND SEALING 31 1058. Effect of the physico-chemical composition of VNB-3 alloy on the operating characteristics of gas-discharge devices. (USSR) Some peculiarities in the behaviour of electrodes made of the metalceramic alloy VNB-3 (93 per cent of W, 5 per cent of Ni and 2 per cent of BaO), in gas-discharge devices, are explained on the basis of the physico-chcmical composition of the alloy. The sharp-focusing character of discharges ending on these electrodes and the considerable decrease in breakdown voltage of spark dischargers using such electrodes, are considered. V M Amosov and B A Kurelin, Elektrovak Tekh, No 52, 1971, 28-31
(in Russian). 31 1059. Predischarge current in a gaseous diode with heated cathode. (USSR) Characteristics of electron current flow in low-pressure gas, in the absence of ionization, are considered. The ratio of the current in vacuum to the current in gas is measured as a function of the hydrogen pressure in the diode. Yu M Zyslin, Elektrovak Tekh, No 51, 1971, 66-70 (in Russian). 31 1060. Machine for gas-electric sealing of a cone to the screen of the glass envelope of an electron-beam tube. (USSR) An horizontal-axis machine for gas-electric sealing of a cone to the screen of the glass envelope of a vacuum electron-beam tube, is described. Glass pieces are heated by gas torches and the sealing process is effecte5 by an electric current applied at high voltage. V L Lizunov et al, Elektrovak Tekh, No 52, 1971, 3-5 (in Russian). 31 1061. Methods of mounting cathode-modulator assemblies of electronbeam tubes. (USSR) A survey of methods of mounting cathode-modulator assemblies of vacuum electron-beam tubes is given. The mounting methods are evaluated from the viewpoint of accuracy and automatization. Mechanical, capacitive, optical and pneumatic methods for adjusting the cathode-modulator distance are considered. V M Grishin et al, Elektrovak Tekh, No 52, 1971, 5-10 (in Russian). 31 1062. Analysis of construction of mechanisms for hermetization of electro-vacuum devices with the aim of their unification. (USSR) The experience of the electro-vacuum industry in sealing mechanisms for glass electro-vacuum devices is discussed. Constructions of sealing mechanism in pumping machines are considered from the viewpoint of developing a unified system. V M Grishin et al, Elektrovak Tekh, No 52, 1971, 10-13 (in Russian). 31 1063. Red phosphors for colour television. (USSR) Results of an investigation on the synthesis of a new class of luminescent materials, based on rare earth elements with red fluorescence
427
German). 30 1051. Device for measuring rates of evaporation in vaeuo. (USSR) A device for measuring rates of evaporation in vacuo of particular value in connection with the deposition of thin metal films is described. Thermo-sensitive elements are placed at different distances from the evaporator and the differences between their readings are recorded. These elements may be simple thermocouples; the energy of the evaporating particles which strike the thermocouples is converted into heat and the latter produces an emf proportional to the amount of matter deposited. The effect of extraneous factors such as radiation on the thermocouples may be compensated, for example, by supplying a small dc current from an external source. The meter recording the emf of the thermocouples may be graduated to read directly in evaporation rates. Yu S Rodichev and Sh A Furman, USSR Patent No 310954, appl lOth Sept 1969, publd 1st Oct 1971. 3O 1052. Electron tunnelling into amorphous InSb and GaSb films. (Germany) The tunnelling of electrons into amorphous InSb and GaSb films has been studied at different temperatures. The tunnel junctions AI-AI~O3-amorphous semiconductor-metal electrode were prepared by evaporation of thin films in a vacuum of 10-e to 10-5 torr. Doping by coevaporation has virtually no influence on the tunnelling characteristics. Diffusion of Cu and Au into the amorphous layer, however, gives a strong increase of the tunelling conductance. C Konak and J Stuke, Phys Stat Sol (a), 9 (1), Jan 1972, 333-341. 30 1053. Copper contamination during the vapour epitaxial growth of GaAs. (Germany) It is shown by photoluminescence measurements that a copper contamination may occur during the vapour epitaxiai growth of GaAs. This contamination occurs both in the epitaxial film and in the substrate. The presence of a level at 0.20 eV above the top of the valence band is introduced in n + doped material, and the corresponding acceptor centre is attributed to a Cuaa-donor complex. (France) E Fabre, Phys Stat Sol (a), 9 (1), Jan 1972, 259-262. 30 1054. A screening device. (USSR) A screening device for use in vacuum systems in connection with the deposition of thin metal films is described. The device consists of a series of lobes set in a circle and rotated by means of a flexible system of springs actuated by a hydraulic cylinder. A special seal is incorporated to prevent loss of vacuum when the screen system is set in motion. Motion is initiated by means of a simple system of levers and springs. One cylinder is provided for the forward motion of the screen and another for returning it to its original position. A A Gordeev et al, USSR Patent No 309980, appl 8th Oct 1969, publd 7th Sept 1971. 30 1055. A vacuum-deposition apparatus with an electron-bcam evaporator. (USSR) A vacuum-deposition apparatus with an electron-beam evaporator for depositing thin metal and semiconducting films is described. The epitaxial growth of germanium films is the principal application. The apparatus comprises an electron gun, together with focusing and deflecting systems and a magnetic prism; the latter serves to rotate the electron beam through 90 ° so as to prevent the accumulation of deposits on the gun itself. As a result of this and other precautions, the evaporator is capable of working reliably for 50 h or more, the chief limiting feature being the life of the gun cathode. The rate of germanium deposition is up to 2 #m/min. Yu P Terent'ev et al, Electronics Industry Scientific-Technical Collection, No 3 (1971), 62, (in Russian). 30 1056. Apparatus for the vacuum deposition of semiconducting-compound films. (USSR) An improved form of apparatus for the vacuum deposition of semiconducting films to be used in electronic devices is described. Unsuitable combinations of temperature and geometry in existing forms of apparatus frequently produce films of non-stoichiometric composition. In the new system the geometry of the principal parts and the
thermal conditions are optimized so as to ensure that the film material shall be deposited from a gas-dynamic flow with a slight super-saturation of the vapour, the material being intensively reevaporated from the substrate and the sides of the vacuum chamber. For example, in the case of CdTe the length/diameter ratio of the chamber should be equal to unity and the temperature gradient 30°C/cm. By using this apparatus stoichiometric films may be repeatedly produced, their principal parameters varying by no more than 20 per cent. Yu Z Bubnov et al, USSR Patent No 309416, appl 17th Feb 1970, publd llth Aug 1971. 30 1057. An evaporation system for vacuum installations. (USSR) An evaporation system for depositing thin metal and other films in electrical vacuum apparatus is described. In contrast to existing devices of this kind, the one here proposed incorporates an elastic electrically-insulating membrane fixed to the current leads, the latter thus being able to move (within certain limits). The operation of the system is more reliable than that of its predecessors. Apart from this, the system contains the usual heating element, evaporation unit, and electrical supplies. The elastic membrane forms the boundary between the evacuated space of the vacuum chamber and the atmosphere. A N Zhanda et al, USSR Patent No 309071, appl 22nd Dec 1969, publd7th Oct 1971. 31. EVACUATION AND SEALING 31 1058. Effect of the physico-chemical composition of VNB-3 alloy on the operating characteristics of gas-discharge devices. (USSR) Some peculiarities in the behaviour of electrodes made of the metalceramic alloy VNB-3 (93 per cent of W, 5 per cent of Ni and 2 per cent of BaO), in gas-discharge devices, are explained on the basis of the physico-chcmical composition of the alloy. The sharp-focusing character of discharges ending on these electrodes and the considerable decrease in breakdown voltage of spark dischargers using such electrodes, are considered. V M Amosov and B A Kurelin, Elektrovak Tekh, No 52, 1971, 28-31
(in Russian). 31 1059. Predischarge current in a gaseous diode with heated cathode. (USSR) Characteristics of electron current flow in low-pressure gas, in the absence of ionization, are considered. The ratio of the current in vacuum to the current in gas is measured as a function of the hydrogen pressure in the diode. Yu M Zyslin, Elektrovak Tekh, No 51, 1971, 66-70 (in Russian). 31 1060. Machine for gas-electric sealing of a cone to the screen of the glass envelope of an electron-beam tube. (USSR) An horizontal-axis machine for gas-electric sealing of a cone to the screen of the glass envelope of a vacuum electron-beam tube, is described. Glass pieces are heated by gas torches and the sealing process is effecte5 by an electric current applied at high voltage. V L Lizunov et al, Elektrovak Tekh, No 52, 1971, 3-5 (in Russian). 31 1061. Methods of mounting cathode-modulator assemblies of electronbeam tubes. (USSR) A survey of methods of mounting cathode-modulator assemblies of vacuum electron-beam tubes is given. The mounting methods are evaluated from the viewpoint of accuracy and automatization. Mechanical, capacitive, optical and pneumatic methods for adjusting the cathode-modulator distance are considered. V M Grishin et al, Elektrovak Tekh, No 52, 1971, 5-10 (in Russian). 31 1062. Analysis of construction of mechanisms for hermetization of electro-vacuum devices with the aim of their unification. (USSR) The experience of the electro-vacuum industry in sealing mechanisms for glass electro-vacuum devices is discussed. Constructions of sealing mechanism in pumping machines are considered from the viewpoint of developing a unified system. V M Grishin et al, Elektrovak Tekh, No 52, 1971, 10-13 (in Russian). 31 1063. Red phosphors for colour television. (USSR) Results of an investigation on the synthesis of a new class of luminescent materials, based on rare earth elements with red fluorescence
427