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1051. Device for measuring rates of evaporation in vacuo
Classified abstracts 1040-1050 30 1040. Preparation and properties of single crystal semiconducting films on insulating substrates. ( H u n g a r y ) Preparation m e t h o d s a n d properties of single crystal s e m i c o n d u c t i n g films on insulating substrates are reviewed. Choice o f a n appropriate substrate is discussed. F o r use in v a c u u m , the substrate material should have a low v a p o u r pressure at the applied temperatures. A d v a n t a g e s o f epitaxial g r o w t h by evaporation in high or ultrahigh v a c u u m using n o r m a l deposition rate, flash or explosion evaporations are shown. Existence o f a n o p t i m u m growth t e m p e r a t u r e o f single crystal films is d e m o n s t r a t e d . ( G e r m a n y ) H Sehoetterer, International Conf Phys Chem Semiconductor Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 1971, 5 28. 30 1041. Theory of high photovoltages in semicondueting films. ( H u n g a r y ) A n o m a l o u s h i g h photovoltages considerably larger t h a n the band gap are observed in obliquely v a c u u m evaporated films of a large n u m b e r o f semiconductors, b o t h elemental a n d c o m p o u n d s . A theory of high p h o t o v o l t a g e in s e m i c o n d u c t i n g films based on a periodicity introduced in processes of deposition, g r o w t h a n d s u b s e q u e n t activation t r e a t m e n t s is presented. (Poland) L Sosnowskl, International Conf Phys Chem Semiconductors Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 1971, 29M0. 30 1042. Semiconductor properties of island films of metal on dielectrics. (Hungary) Properties a n d structure o f island A u films on NaCI obtained by sputtering a n d t h e r m a l evaporation are investigated a n d c o m p a r e d using electron microscopic a n d electron diffraction methods. Sputtering was p e r f o r m e d in a n a t m o s p h e r e of a r g o n tinder a pressure o f 5 x 10 -2 torr, at voltage of 2 kV a n d discharge current density of I m A / c m ~. E v a p o r a t i o n of gold was performed at residual gas pressure of 10 -s torr f r o m a t u n g s t e n basket. In both cases the temperature o f substrates was 300°C. T h e relation between electrical properties a n d the structure of island films is discussed. (USSR) B T Boiko et al, International Conf Phys Chem Semiconductors
Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest, 1971, 73-86. 30 1043. Photoelectric properties of amorphous chalcogenide semiconducting layers. ( H u n g a r y ) Photoelectric properties of a m o r p h o u s chalcogenide s e m i c o n d u c t i n g films with c o m p o s i t i o n s As~Te3, As2~Tes0Si~5, As30Te~0SiHGe9 a n d As20Te60Siz0 are investigated. T h e films were deposited in v a c u u m at 10 -s torr on a m o r p h o u s silica or glass substrates kept at r o o m temperature. ( R o m a n i a ) T Botilia et al, lnternatienal ConfPhys Chem Semiconductors Heterojunctions Layer Structure., Vol 4, Akademiai Kiado Budapest 1971, 87 96. 30 1044. Electrical transport and structure of vacuum deposited carbon films. ( H u n g a r y ) Results o f systematic investigation of the structural, electrical a n d optical properties of a m o r p h o u s c a r b o n films deposited in v a c u u m are presented. A m o r p h o u s c a r b o n films were deposited on fused silica substrates held at r o o m temperature, using a high-power electron g u n in a v a c u u m less t h a n 5 x 10 -s torr. Spectrally pure carbon rods were used as starting material. Electrical c o n d u c t i o n and Seebeck effect were m e a s u r e d between p l a t i n u m evaporated electrodes in v a c u u m at pressure lower t h a n 5 ¢: i0 6 torr. T h e film thicknesses were between 800 a n d 2000 ~ , as determined by the T o l a n s k y interferometric m e t h o d . It is f o u n d that a m o r p h o u s c a r b o n films obtained by v a c u u m deposition using an electron g u n are p-type, lowmobility semiconductors. Electron diffraction data show' that a n n e a l e d a m o r p h o u s c a r b o n films are very stable, the structure showing no traces o f crystalline graphite even after a heat t r e a t m e n t at 1575°K. ( R u m a n i a ) A Devenyi et al, International Conf Phys Chem Semiconductors
Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 1971, 97-104. 30 1045. Electrical and structural properties of sputtered Ge and G e , T e ~ , films. ( H u n g a r y ) Electrical transport properties a n d structure of sputtered Ge a n d
426
Ge,Te~. ~ films (x .0.8) are investigated. T h e films were obtained by sputtering in pure argon using either the diode or the triode m e t h o d . T h e substrate consisted of fused silica or freshly air-cleaved NaCI crystals kept at r o o m temperature during deposition. T h e cathode was m a d e of a pure Ge plate with given fraction of its surface previously covered with Te by v a c u u m deposition. T h e actual Te concentration in the films was m e a s u r e d using an electron microprobe analyzer. Thickness of the films was between 500 a n d 50,000/~. It is found that the m a i n difference in the electrical properties of evaporated a n d sputtered a m o r p h o u s films is due to the occlusion of argon a t o m s during f o r m a t i o n o f the films by sputtering. After an appropriate heat treatment (desorption of gases) the films obtained by both m e t h o d s tend to have the s a m e properties. A Devenyi et al, International Conf Phys Chem Semiconductors
Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 1971, 105 113. 30 1046. Dielectric properties of thin ZnS layers. ( H u n g a r y ) T h e relative dielectric c o n s t a n t and the loss factor o f thin Z n S films, with thickness of 100 A. to 1 /~m, are measured. T h e Z n S films were electron b e a m evaporated in v a c u u m at 4:d 10 -4 torr on glass substrates at different temperatures with the deposition rate of 5 A/sec. Electron microscope investigations showed that the films are c o m posed of hexagonal a n d cubic polycrystals. P Gottwald and El Sayed Mahfouz Hassan lbrahim, International
Conf Phys Chem Semiconductors Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 197 I, 127-13 I. 30 1047. Effect of the structure on electrical and optical properties of lnSb, GaSb and InxGaa -xSb alloys single crystalline films. ( H u n g a r y ) Results of an investigation on the effect of experimental g r o w t h conditions on the properties o f single crystal films of InSb, G a S b a n d InxGa~ ~Sb a n d the perfection o f their structure, are presented. Films containing up to 50 tool per cent of G a S b were obtained by recrystallizing molten polycrystalline films initially prepared by flash evaporation o n t o heated mica, a m o r p h o u s quartz, and sapphire platelets. C o m p o s i t i o n s with m o r e t h a n 50 tool per cent of G a S b were epitaxially deposited by evaporation onto freshly cleaved slabs o f lnSb, GaSb, G a A s , CdTe, Z n T e a n d ZnSe. in both m e t h o d s the evaporation was carried out in a v a c u u m of a b o u t 10-:' torr. Structure of the films was investigated by x-ray a n d electron diffraction. Electrical a n d optical properties of the films were studied. ( U S S R ) V A Kassyan et al, International Conf Phys Chem Semiconductors Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 1971,133 142. 3O 1048. Electrical and optical properties of germanium films on insulating substrates. ( H u n g a r y ) Electrical, optical, surface a n d structural properties of g e r m a n i u m films, 3 to 5 /ml thick, v a c u u m c o n d e n s e d on semi-insulating G a A s a n d ferroelectric BaxSrt_,TiO:~ ceramic substrates, are studied. Depending on t e m p e r a t u r e of the substrate when coated with Ge, the film structure on G a A s varied from polycrystalline to m o n o c r y s t a l line. G e films on ceramics were polycrystalline with various degrees of ordering but p r e d o m i n a n t l y (100) orientation. T h e Ge films were p-type. (USSR) A P Klimenko et al, International Conf Phys Chem Semiconductors Heterojunctions Layer Structures, Vol 4, Akademiui Kiado Budapest 1971, 143 150. 30 1049. CdOxSe~ x phases in vacuum deposited films of CdSe. ( G e r m a n y ) CdSe films with a good orientation were obtained by v a c u u m deposition of CaF2 by an appropriate substrate t e m p e r a t u r e a n d deposition rate in a v a c u u m of better t h a n 10-:' torr. However, in s o m e cases CdO=Se~ .~ phases were present in the films as was revealed by electron diffraction methods. It is s h o w n that at pressure of a b o u t 10 -s tort a considerable a m o u n t of oxygen m a y still be built into the lattice of the CdSe film. L Daweritz and A Messrschmidt, Phys Stat Sol (a), 4 (3), 1971, K193 KI96. 30 1050. Mierofractography for observation of recrystallization in CdSe evaporated films. ( G e r m a n y ) Recrystallization in v a c u u m evaporated films o f CdSe, subjected to tempering in high v a c u u m at 10 -6 torr a n d under c a d m i u m saturated
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
Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest, 1971, 73-86. 30 1043. Photoelectric properties of amorphous chalcogenide semiconducting layers. ( H u n g a r y ) Photoelectric properties of a m o r p h o u s chalcogenide s e m i c o n d u c t i n g films with c o m p o s i t i o n s As~Te3, As2~Tes0Si~5, As30Te~0SiHGe9 a n d As20Te60Siz0 are investigated. T h e films were deposited in v a c u u m at 10 -s torr on a m o r p h o u s silica or glass substrates kept at r o o m temperature. ( R o m a n i a ) T Botilia et al, lnternatienal ConfPhys Chem Semiconductors Heterojunctions Layer Structure., Vol 4, Akademiai Kiado Budapest 1971, 87 96. 30 1044. Electrical transport and structure of vacuum deposited carbon films. ( H u n g a r y ) Results o f systematic investigation of the structural, electrical a n d optical properties of a m o r p h o u s c a r b o n films deposited in v a c u u m are presented. A m o r p h o u s c a r b o n films were deposited on fused silica substrates held at r o o m temperature, using a high-power electron g u n in a v a c u u m less t h a n 5 x 10 -s torr. Spectrally pure carbon rods were used as starting material. Electrical c o n d u c t i o n and Seebeck effect were m e a s u r e d between p l a t i n u m evaporated electrodes in v a c u u m at pressure lower t h a n 5 ¢: i0 6 torr. T h e film thicknesses were between 800 a n d 2000 ~ , as determined by the T o l a n s k y interferometric m e t h o d . It is f o u n d that a m o r p h o u s c a r b o n films obtained by v a c u u m deposition using an electron g u n are p-type, lowmobility semiconductors. Electron diffraction data show' that a n n e a l e d a m o r p h o u s c a r b o n films are very stable, the structure showing no traces o f crystalline graphite even after a heat t r e a t m e n t at 1575°K. ( R u m a n i a ) A Devenyi et al, International Conf Phys Chem Semiconductors
Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 1971, 97-104. 30 1045. Electrical and structural properties of sputtered Ge and G e , T e ~ , films. ( H u n g a r y ) Electrical transport properties a n d structure of sputtered Ge a n d
426
Ge,Te~. ~ films (x .0.8) are investigated. T h e films were obtained by sputtering in pure argon using either the diode or the triode m e t h o d . T h e substrate consisted of fused silica or freshly air-cleaved NaCI crystals kept at r o o m temperature during deposition. T h e cathode was m a d e of a pure Ge plate with given fraction of its surface previously covered with Te by v a c u u m deposition. T h e actual Te concentration in the films was m e a s u r e d using an electron microprobe analyzer. Thickness of the films was between 500 a n d 50,000/~. It is found that the m a i n difference in the electrical properties of evaporated a n d sputtered a m o r p h o u s films is due to the occlusion of argon a t o m s during f o r m a t i o n o f the films by sputtering. After an appropriate heat treatment (desorption of gases) the films obtained by both m e t h o d s tend to have the s a m e properties. A Devenyi et al, International Conf Phys Chem Semiconductors
Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 1971, 105 113. 30 1046. Dielectric properties of thin ZnS layers. ( H u n g a r y ) T h e relative dielectric c o n s t a n t and the loss factor o f thin Z n S films, with thickness of 100 A. to 1 /~m, are measured. T h e Z n S films were electron b e a m evaporated in v a c u u m at 4:d 10 -4 torr on glass substrates at different temperatures with the deposition rate of 5 A/sec. Electron microscope investigations showed that the films are c o m posed of hexagonal a n d cubic polycrystals. P Gottwald and El Sayed Mahfouz Hassan lbrahim, International
Conf Phys Chem Semiconductors Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 197 I, 127-13 I. 30 1047. Effect of the structure on electrical and optical properties of lnSb, GaSb and InxGaa -xSb alloys single crystalline films. ( H u n g a r y ) Results of an investigation on the effect of experimental g r o w t h conditions on the properties o f single crystal films of InSb, G a S b a n d InxGa~ ~Sb a n d the perfection o f their structure, are presented. Films containing up to 50 tool per cent of G a S b were obtained by recrystallizing molten polycrystalline films initially prepared by flash evaporation o n t o heated mica, a m o r p h o u s quartz, and sapphire platelets. C o m p o s i t i o n s with m o r e t h a n 50 tool per cent of G a S b were epitaxially deposited by evaporation onto freshly cleaved slabs o f lnSb, GaSb, G a A s , CdTe, Z n T e a n d ZnSe. in both m e t h o d s the evaporation was carried out in a v a c u u m of a b o u t 10-:' torr. Structure of the films was investigated by x-ray a n d electron diffraction. Electrical a n d optical properties of the films were studied. ( U S S R ) V A Kassyan et al, International Conf Phys Chem Semiconductors Heterojunctions Layer Structures, Vol 4, Akademiai Kiado Budapest 1971,133 142. 3O 1048. Electrical and optical properties of germanium films on insulating substrates. ( H u n g a r y ) Electrical, optical, surface a n d structural properties of g e r m a n i u m films, 3 to 5 /ml thick, v a c u u m c o n d e n s e d on semi-insulating G a A s a n d ferroelectric BaxSrt_,TiO:~ ceramic substrates, are studied. Depending on t e m p e r a t u r e of the substrate when coated with Ge, the film structure on G a A s varied from polycrystalline to m o n o c r y s t a l line. G e films on ceramics were polycrystalline with various degrees of ordering but p r e d o m i n a n t l y (100) orientation. T h e Ge films were p-type. (USSR) A P Klimenko et al, International Conf Phys Chem Semiconductors Heterojunctions Layer Structures, Vol 4, Akademiui Kiado Budapest 1971, 143 150. 30 1049. CdOxSe~ x phases in vacuum deposited films of CdSe. ( G e r m a n y ) CdSe films with a good orientation were obtained by v a c u u m deposition of CaF2 by an appropriate substrate t e m p e r a t u r e a n d deposition rate in a v a c u u m of better t h a n 10-:' torr. However, in s o m e cases CdO=Se~ .~ phases were present in the films as was revealed by electron diffraction methods. It is s h o w n that at pressure of a b o u t 10 -s tort a considerable a m o u n t of oxygen m a y still be built into the lattice of the CdSe film. L Daweritz and A Messrschmidt, Phys Stat Sol (a), 4 (3), 1971, K193 KI96. 30 1050. Mierofractography for observation of recrystallization in CdSe evaporated films. ( G e r m a n y ) Recrystallization in v a c u u m evaporated films o f CdSe, subjected to tempering in high v a c u u m at 10 -6 torr a n d under c a d m i u m saturated
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
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