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Characterisation of I2L gates
between the spin density and the linewidth is found out for undoped samples suggesting that the localized states are uniformly annealed out up to 1050C in spite of the crystallization of the samples at 700 ~ 800~C. The spin density also decreases with an increase of doping ratio, but the linewidth remains constant. For a heavily doped sample, a new signal with g = 2.0043 is observed, and suggested to be due to localized states associated with incorporated phosphorus atoms. llighly insulating silicon nitride films FATEtt M O H A M M A D NAZAR Int. J. Electron. 46, (I) 57 (1979). Highly insulating silicon nitride films are obtained when the nitride is deposited on silicon wafers coated with tungsten. Current conduction in these films follows a high power law of the form 1 oc V" with values of n greater than 10, as compared to silicon nitride films deposited on silicon which give log I - V " " behaviour. C - V curves and infra-red absorption measurements indicate that in the tungsten-coated samples, either the tungsten layer has disappeared during the deposition process and has been incorporated in the nitride and "doped" it in the process, or the tungsten layer might be in the island (three-dimensional growth) form which may transmit in the infra-red.
3. Testing Ultra-high vacuum systems for surface research Y. M A R G O N I N S K I Vacuum 28, (12) 515. During the last 20 years, surface research has been one of the fastest growing fields in physics and physical chemistry. Yet such a development would have been impossible without a parallel advance in ultra-high vacuum (uhv) techniques. In this paper a short survey is given of uhv systems in surface research from 1927 to the present day, with special emphasis on the developments since the 1950s when N A S A was established. To illustrate modern uhv technology, a detailed description his given of two commercially available systems, specially designed for surface research.
Characterlsation of IZL gates H. E. J. WU LMS Microelectron. J. 9, (2) 4 (1978). With the aid of only three straightforwzrd measurements the electrical behaviour of 12L gates can be characterised. For a given technnological process a practical method is described which uses these measured data in order to construct a set of nomograms. These nomograms can be used to evaluate the influence of the number of collectors and the lateral pnp base width upon the current amplification of an IZL gate. They can further be used to decide whether perpendicular or parallel current injection has to be applied. The theoretical background of the construction of the nomograms is given. A microelectronie test pattern for analyzing automated z afer probing and probe card problems RICHARD L. MATTIS and MELVIN R. D O G G E T T Solid St. Technol. p. 76 (November 1978). The testing of integrated circuits or test patterns at the wafer level requires reliable probing capa'bility in order that apparent defects or device failures can be cgnfidently attributed to processing problems rather than probing problems. A test pattern has been developed which consists primarily of interconnected probe pads of several sizes. Using this pattern, high-speed probing capability can be evaluated, and probing problems such as misorientation be4tween wafer and probes and prober run-out can be detected.
Fracture strength of silicon ~afers D. C. GUIDICI Microelectronics 9, (I) 14 (1978). A simple testing method is described for measuring the fracture strength of silicon wafers. It is applied to dctcrmine tile comparative strengths of wafers cut from crystals grown by Czochralski and floatzone methods, when the wafers have different surface orientation, with and without edge rounding, and with differing amounts of surface work damage after the sawing process.
Recombination: A sur,ey N. F. MOTT Solid-St. Electron. 21, 1275 (1978). Auger, optical, multiphonon and cascade are the main recombination processes known. Carriers can recombine from band to band, or after they have formed an exciton, or after one or both are trapped at an impurity or defect. This paper gives attention to recombination by bound and free excitons, and wide-gap materials are discussed as well as semiconductors, because the recombination mechanisms are often better understood. We treat particularly the competition between radiative and multiphonon process, including that of Dexter, Klick and Russell. It is pointed out that cascade trapping by a charged centre does not always give rise to a large ( ~ 1 0 - t ' c m ") cross section. Exciton lifetime and fluorescence are described. Configuration diagrams are illustrated by the cases of I~, centres and similar behaviour in semiconductors where the valence band is of lone pair type and in insulators such as AszTe 3 and SiOz. Recombination in some amorphous semiconductors is contrasted with that in crystals; SiO 2 presents some special problems. Finally the effect of magnetic field and an ESR signal is described. Microwave heating and esaporating of a large electron-hole drop in pure Ge V. P. AKSENOV, B. G. Z H U R K I N and M. ROSSO Solid St. Commnn. 28, 537 (1978). At the large microwave power level, we have observed a sharp increase of the m.w. absorption in magnetic field and an appearance of steps in the m.w. absorption kinetics. These steps are connected with the intense evaporation of drops caused by the m.w. field, which provides the existence of the dense cloud of free carriers surrounding the drop. The density of the cloud has been found to depend strongly on magnetic field.
Thermal conductivity variation of sillcon ~ith temperature CHANDRA PRAKASH Microelectron. Reliab. 18, 333 (1978). In the present paper a mathematical relation has been developed to explain the variation of thermal conductivity of silicon from room temperature to its melting point quite accurately. The theoretical results obtained for various temperatures have been compared with the experimental results. Design forethought promotes easier testing of microcomputer boards MICHAEL D. L I P P M A N and EDWARD S. D O N N Electronics p. 113 (18 January 1979). Three key considerations are: using microcomputers" self-test capabilities, adopting new diagnostic algorithms, and designing the system for testability.
The generation of point defects in GaAs by electron-hole recombination at dislocations P. W. HUTCHINSON, P. S. DOBSON, B. W A K E F I E L D and S. O'ttARA Solid-St. Electron. 21, 1413 (1978). The degradation of GaAs heterojunction lasers results in the formation of long dislocation dipoles which grow by a climb process involving point defect concentrations of the order of 10 m9 cm-3. The driving force for this climb process is not understood and it has been suggested that the material contains a supersaturation of native interstitials which condense on the dislocation during device operation. An alternative model proposed that the driving force is related to the energy released by electron-hole recombination on the dislocation which is partially dissipated by the dislocation emitting vacancies into the surrounding lattice. Gallium arsenide substrates containing greater than 2 x 10 ~8 tellurium atoms cm -3 contain interstitial concentrations of the order of l0 t 7 cm-3 which condense out to form small dislocation loops during an anneal at 880~C. The presence of these loops indicates that the annealed material does not contain excess interstitials in solution. This annealed material was optically pumped and examined by transmission electron microscopy. It was found that the loops developed into dipoles typical of degraded lasers. The number of point defects involved in this climb process increased with increasing pumping 41
3. Testing Ultra-high vacuum systems for surface research Y. M A R G O N I N S K I Vacuum 28, (12) 515. During the last 20 years, surface research has been one of the fastest growing fields in physics and physical chemistry. Yet such a development would have been impossible without a parallel advance in ultra-high vacuum (uhv) techniques. In this paper a short survey is given of uhv systems in surface research from 1927 to the present day, with special emphasis on the developments since the 1950s when N A S A was established. To illustrate modern uhv technology, a detailed description his given of two commercially available systems, specially designed for surface research.
Characterlsation of IZL gates H. E. J. WU LMS Microelectron. J. 9, (2) 4 (1978). With the aid of only three straightforwzrd measurements the electrical behaviour of 12L gates can be characterised. For a given technnological process a practical method is described which uses these measured data in order to construct a set of nomograms. These nomograms can be used to evaluate the influence of the number of collectors and the lateral pnp base width upon the current amplification of an IZL gate. They can further be used to decide whether perpendicular or parallel current injection has to be applied. The theoretical background of the construction of the nomograms is given. A microelectronie test pattern for analyzing automated z afer probing and probe card problems RICHARD L. MATTIS and MELVIN R. D O G G E T T Solid St. Technol. p. 76 (November 1978). The testing of integrated circuits or test patterns at the wafer level requires reliable probing capa'bility in order that apparent defects or device failures can be cgnfidently attributed to processing problems rather than probing problems. A test pattern has been developed which consists primarily of interconnected probe pads of several sizes. Using this pattern, high-speed probing capability can be evaluated, and probing problems such as misorientation be4tween wafer and probes and prober run-out can be detected.
Fracture strength of silicon ~afers D. C. GUIDICI Microelectronics 9, (I) 14 (1978). A simple testing method is described for measuring the fracture strength of silicon wafers. It is applied to dctcrmine tile comparative strengths of wafers cut from crystals grown by Czochralski and floatzone methods, when the wafers have different surface orientation, with and without edge rounding, and with differing amounts of surface work damage after the sawing process.
Recombination: A sur,ey N. F. MOTT Solid-St. Electron. 21, 1275 (1978). Auger, optical, multiphonon and cascade are the main recombination processes known. Carriers can recombine from band to band, or after they have formed an exciton, or after one or both are trapped at an impurity or defect. This paper gives attention to recombination by bound and free excitons, and wide-gap materials are discussed as well as semiconductors, because the recombination mechanisms are often better understood. We treat particularly the competition between radiative and multiphonon process, including that of Dexter, Klick and Russell. It is pointed out that cascade trapping by a charged centre does not always give rise to a large ( ~ 1 0 - t ' c m ") cross section. Exciton lifetime and fluorescence are described. Configuration diagrams are illustrated by the cases of I~, centres and similar behaviour in semiconductors where the valence band is of lone pair type and in insulators such as AszTe 3 and SiOz. Recombination in some amorphous semiconductors is contrasted with that in crystals; SiO 2 presents some special problems. Finally the effect of magnetic field and an ESR signal is described. Microwave heating and esaporating of a large electron-hole drop in pure Ge V. P. AKSENOV, B. G. Z H U R K I N and M. ROSSO Solid St. Commnn. 28, 537 (1978). At the large microwave power level, we have observed a sharp increase of the m.w. absorption in magnetic field and an appearance of steps in the m.w. absorption kinetics. These steps are connected with the intense evaporation of drops caused by the m.w. field, which provides the existence of the dense cloud of free carriers surrounding the drop. The density of the cloud has been found to depend strongly on magnetic field.
Thermal conductivity variation of sillcon ~ith temperature CHANDRA PRAKASH Microelectron. Reliab. 18, 333 (1978). In the present paper a mathematical relation has been developed to explain the variation of thermal conductivity of silicon from room temperature to its melting point quite accurately. The theoretical results obtained for various temperatures have been compared with the experimental results. Design forethought promotes easier testing of microcomputer boards MICHAEL D. L I P P M A N and EDWARD S. D O N N Electronics p. 113 (18 January 1979). Three key considerations are: using microcomputers" self-test capabilities, adopting new diagnostic algorithms, and designing the system for testability.
The generation of point defects in GaAs by electron-hole recombination at dislocations P. W. HUTCHINSON, P. S. DOBSON, B. W A K E F I E L D and S. O'ttARA Solid-St. Electron. 21, 1413 (1978). The degradation of GaAs heterojunction lasers results in the formation of long dislocation dipoles which grow by a climb process involving point defect concentrations of the order of 10 m9 cm-3. The driving force for this climb process is not understood and it has been suggested that the material contains a supersaturation of native interstitials which condense on the dislocation during device operation. An alternative model proposed that the driving force is related to the energy released by electron-hole recombination on the dislocation which is partially dissipated by the dislocation emitting vacancies into the surrounding lattice. Gallium arsenide substrates containing greater than 2 x 10 ~8 tellurium atoms cm -3 contain interstitial concentrations of the order of l0 t 7 cm-3 which condense out to form small dislocation loops during an anneal at 880~C. The presence of these loops indicates that the annealed material does not contain excess interstitials in solution. This annealed material was optically pumped and examined by transmission electron microscopy. It was found that the loops developed into dipoles typical of degraded lasers. The number of point defects involved in this climb process increased with increasing pumping 41