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Microcomputer applications in telephony
490
World Abstracts on Microelectronics and Reliability
Microprocessors in telecommunication systems. DAN C. STANZlONE. Proc. IEEE 66, (2) 192 (February 1978). An
cation of microcomputers and other large-scale integrated (LSI) circuit products such as microcomputer memory peripherals, digital coders and decoders Icodccl. and channel filters to telephone switching systems, transmission systems, and to high-feature telephone instruments is discussed. Switching and transmission s3stems which use standardized digital transmission formats arc describe& and line circuit and c o m m o n control functions are briefly discussed for digital switching system architectures using microcomputer control. A high-feature elctronic telephone and trends in digital telephony are also reviewed as thc~ relate to potential applications of produc!~ based on large scale integration techniques.
overview of the ways in which the microprocessor is impacting the design of telecommunication systems is presented. The concept of the microprocessor as a software customized, catalog device is discussed. The various processor structures which are being employed in telecommunication systems utilizing microprocessors are emphasized and several examples are described.
Microcomputer applications in telephony. DONALD K, MELVIN, Proc. IEEE 66, (2) 182 (February 1978). The appli7. S E M I C O N D U C T O R
INTEGRATED
CIRCUITS,
Comments on "'Experimental evidence against the shell model of bound muMexciton complexes in silicon". M. L. THEWALT. Solid St. Commun. 25, 513 (1978). The recent claims of the refutation of Kirczenow's shell model of the bound multiexciton complexes are shown to be without foundation. It is shown that the shell model does in fact explain much of the piezospectroscopic data upon which those claims were, in part, based. Furthermore, the timeresolved luminescence data which appeared to convincingly rule out the shell model are shown to be in disagreement with the detailed time-resolved studies reported here. The present studies support the shell model, and a possible cause for the discrepancy between the two sets of data is suggested.
Theory of the mobility of electrons limited by charged impurities in two dimensions. B. FELL, J. T. CHEN. J. HARD'~, M. PRASAD and S. FUJITA. J. Phys. Chem. Solids 39, 221 11978). The mobility ~ of electrons limited by charged impurities in two dimensions is calculated, based on the proper connected diagram expansion of Kubo's formula. For a Coulomb-type interaction, the Boltzmann relaxation rate is r ~°~ = 2n2h - lnlm*22e4K-2p-2, where nt represents the concentration of the impurities, and x the dielectric constant. This leads to a mobility proportional to temperature T for non-degenerate electrons. The quasi-particle effect, which is self-consistently contained in the proper connected diagram expansion, yields an equation for the relaxation rate r. The solution of this equation yields values in general reduced relative to !~0~ at higher densities. The values of 11 obtained in our calculations, are higher than those predicted by the Boltzmann theory, and deviations are pronounced at low temperatures.
Electrical characteristics of sputtering-induced defects in n-type silicon. L. P. ANDERSSON and A. O E\,WARAYE. Vacuum 28, (1) 5. The electrical characteristics of the sputtering induced defects have been studied using the DLTS measurements. A band of defect states located at E~ 0.3 eV to E~q).5 eV was found. The measured capture cross-section for majority carriers at this band is 1.3 x 10 ~ c m 2. The concentration profile of this band of defects decreases exponentially from the surface. This initial concentration of the defects near the surface of a sputtered platinum silicide diode is extrapolated to 7 x 10 ~v cm -a. The defects anneal out after 10 rain of annealing time at 4 0 0 C .
Stationary model of the chemical vapour deposition of homoepitaxial silicon layers. JACEK KOREC and JERZV BoaKOWICZ. Electron Technol. 10, (3) 3 (1977). A theoretical model of chemical vapour deposition of epitaxial Si layers is developed. The model is next applied to the case of hydrogen reduction of SiCI4. It is assumed that, depending on the content of reagents involved (SiCI4-H2) and substrate temperature, the growth process is controlled by
DEVICES
AND
MATERIALS
mass transport in gas phase (diffusion m slagnant layer), surface chemical reaction and/or surface saturation v, Jlh reaction products. Experimental determination of the par ameters of the obtained equation is presented. It is shown that in the temperature range 900 1300'C and for SiC14/H2 molar ratios smaller than 1%. lhe error between the calculated and experimental values of growth rate is the same as that originating from repeatability of epitaxial unit and the measurement technique used m experiments
Significance of GaAs solubility in Ga-AI Alloys in multilayer LPE of AI.Ga~_.As. M?,RC'~rJ PISKORSb:I and Zm~,NIEW MUSZYNSKI. Electron Tcchnol. 10, (3i 27 (1977). The solubility of GaAs in Ga~ AI alloy with different AI contents in the liquid phase was investigated by means of the liquid phase epitaxy in Ihe temperature range of 800 1000(.7. The experimental results were then con> pared lo the calculated solubility xalue. [ h e y were [ound to be in high accordance with the theoretical ones. The results obtained will permit an o p t i m u m conirol t?[ the process of growth the multilayer structures such a': ~J:'" GaAs "p'" GaAs "~1~.... AI,Ga .~As ol "'rf" (iaAs "'tf" AI~Gal ~As [or "p'" GaAs) "p-'" Al~(ia~ ,As "p'" GaAs which are used in heterojunction lasers and LEDs, emiting radiation in wide range of wavelength.
The band structure dependence of impact ionization b> hot carriers in semiconductors: GaAs. T. P. Pt-~ARSM.t. Solid-St. Electron. 21, 297 (1978). We present lhe first s>stematic study of the dependence of impact ionization by electrons and holes upon the details of the electronic band slruclure. Our measurements, made in GaAs. establish the crucial role of the ionization threshold energy, and its location in the Brillouin zone, in determining the ionizatiou rates. This relationship is apparent in the dependence of tmpact ionization rates on the temperature of the lattice, compositional changes for the alloy GaAsi ,Sb,, and the orientation and strength of the electric field. The strong dependence of impact ionization upon specific features of the electronic band structure is a new principle whicia ca~ be used to study the nature of electronic states in a wide xariety of semiconductors through hot-carrier behavior
Electron transport and ionization in silicon at high fields. H. P. D. LANYON. Solid-St. Electron. 21, 291 (1978i, The saturated drift velocity measured for electrons at high fields is inconsistent with Shockley's model for impact ionization in silicon, It is explained in terms of a field-dependem mean free path for high energy phonon creation in the electric field direction, electrons creating a high energy p h o n o n as soon as they have acquired su¢ficient energy from the field. Assuming that the electron wavepacket travels at the saturated drift velocity without dispersion, it can be shown thai the increased scattering rate at high fields must result in a large spread in lhe carrier energy..
World Abstracts on Microelectronics and Reliability
Microprocessors in telecommunication systems. DAN C. STANZlONE. Proc. IEEE 66, (2) 192 (February 1978). An
cation of microcomputers and other large-scale integrated (LSI) circuit products such as microcomputer memory peripherals, digital coders and decoders Icodccl. and channel filters to telephone switching systems, transmission systems, and to high-feature telephone instruments is discussed. Switching and transmission s3stems which use standardized digital transmission formats arc describe& and line circuit and c o m m o n control functions are briefly discussed for digital switching system architectures using microcomputer control. A high-feature elctronic telephone and trends in digital telephony are also reviewed as thc~ relate to potential applications of produc!~ based on large scale integration techniques.
overview of the ways in which the microprocessor is impacting the design of telecommunication systems is presented. The concept of the microprocessor as a software customized, catalog device is discussed. The various processor structures which are being employed in telecommunication systems utilizing microprocessors are emphasized and several examples are described.
Microcomputer applications in telephony. DONALD K, MELVIN, Proc. IEEE 66, (2) 182 (February 1978). The appli7. S E M I C O N D U C T O R
INTEGRATED
CIRCUITS,
Comments on "'Experimental evidence against the shell model of bound muMexciton complexes in silicon". M. L. THEWALT. Solid St. Commun. 25, 513 (1978). The recent claims of the refutation of Kirczenow's shell model of the bound multiexciton complexes are shown to be without foundation. It is shown that the shell model does in fact explain much of the piezospectroscopic data upon which those claims were, in part, based. Furthermore, the timeresolved luminescence data which appeared to convincingly rule out the shell model are shown to be in disagreement with the detailed time-resolved studies reported here. The present studies support the shell model, and a possible cause for the discrepancy between the two sets of data is suggested.
Theory of the mobility of electrons limited by charged impurities in two dimensions. B. FELL, J. T. CHEN. J. HARD'~, M. PRASAD and S. FUJITA. J. Phys. Chem. Solids 39, 221 11978). The mobility ~ of electrons limited by charged impurities in two dimensions is calculated, based on the proper connected diagram expansion of Kubo's formula. For a Coulomb-type interaction, the Boltzmann relaxation rate is r ~°~ = 2n2h - lnlm*22e4K-2p-2, where nt represents the concentration of the impurities, and x the dielectric constant. This leads to a mobility proportional to temperature T for non-degenerate electrons. The quasi-particle effect, which is self-consistently contained in the proper connected diagram expansion, yields an equation for the relaxation rate r. The solution of this equation yields values in general reduced relative to !~0~ at higher densities. The values of 11 obtained in our calculations, are higher than those predicted by the Boltzmann theory, and deviations are pronounced at low temperatures.
Electrical characteristics of sputtering-induced defects in n-type silicon. L. P. ANDERSSON and A. O E\,WARAYE. Vacuum 28, (1) 5. The electrical characteristics of the sputtering induced defects have been studied using the DLTS measurements. A band of defect states located at E~ 0.3 eV to E~q).5 eV was found. The measured capture cross-section for majority carriers at this band is 1.3 x 10 ~ c m 2. The concentration profile of this band of defects decreases exponentially from the surface. This initial concentration of the defects near the surface of a sputtered platinum silicide diode is extrapolated to 7 x 10 ~v cm -a. The defects anneal out after 10 rain of annealing time at 4 0 0 C .
Stationary model of the chemical vapour deposition of homoepitaxial silicon layers. JACEK KOREC and JERZV BoaKOWICZ. Electron Technol. 10, (3) 3 (1977). A theoretical model of chemical vapour deposition of epitaxial Si layers is developed. The model is next applied to the case of hydrogen reduction of SiCI4. It is assumed that, depending on the content of reagents involved (SiCI4-H2) and substrate temperature, the growth process is controlled by
DEVICES
AND
MATERIALS
mass transport in gas phase (diffusion m slagnant layer), surface chemical reaction and/or surface saturation v, Jlh reaction products. Experimental determination of the par ameters of the obtained equation is presented. It is shown that in the temperature range 900 1300'C and for SiC14/H2 molar ratios smaller than 1%. lhe error between the calculated and experimental values of growth rate is the same as that originating from repeatability of epitaxial unit and the measurement technique used m experiments
Significance of GaAs solubility in Ga-AI Alloys in multilayer LPE of AI.Ga~_.As. M?,RC'~rJ PISKORSb:I and Zm~,NIEW MUSZYNSKI. Electron Tcchnol. 10, (3i 27 (1977). The solubility of GaAs in Ga~ AI alloy with different AI contents in the liquid phase was investigated by means of the liquid phase epitaxy in Ihe temperature range of 800 1000(.7. The experimental results were then con> pared lo the calculated solubility xalue. [ h e y were [ound to be in high accordance with the theoretical ones. The results obtained will permit an o p t i m u m conirol t?[ the process of growth the multilayer structures such a': ~J:'" GaAs "p'" GaAs "~1~.... AI,Ga .~As ol "'rf" (iaAs "'tf" AI~Gal ~As [or "p'" GaAs) "p-'" Al~(ia~ ,As "p'" GaAs which are used in heterojunction lasers and LEDs, emiting radiation in wide range of wavelength.
The band structure dependence of impact ionization b> hot carriers in semiconductors: GaAs. T. P. Pt-~ARSM.t. Solid-St. Electron. 21, 297 (1978). We present lhe first s>stematic study of the dependence of impact ionization by electrons and holes upon the details of the electronic band slruclure. Our measurements, made in GaAs. establish the crucial role of the ionization threshold energy, and its location in the Brillouin zone, in determining the ionizatiou rates. This relationship is apparent in the dependence of tmpact ionization rates on the temperature of the lattice, compositional changes for the alloy GaAsi ,Sb,, and the orientation and strength of the electric field. The strong dependence of impact ionization upon specific features of the electronic band structure is a new principle whicia ca~ be used to study the nature of electronic states in a wide xariety of semiconductors through hot-carrier behavior
Electron transport and ionization in silicon at high fields. H. P. D. LANYON. Solid-St. Electron. 21, 291 (1978i, The saturated drift velocity measured for electrons at high fields is inconsistent with Shockley's model for impact ionization in silicon, It is explained in terms of a field-dependem mean free path for high energy phonon creation in the electric field direction, electrons creating a high energy p h o n o n as soon as they have acquired su¢ficient energy from the field. Assuming that the electron wavepacket travels at the saturated drift velocity without dispersion, it can be shown thai the increased scattering rate at high fields must result in a large spread in lhe carrier energy..