- Email: [email protected]
Neuron-like transient phenomena in silicon p-i-n structures
662
World Abstracts on Microelectronics and Reliability
Technol. 19(3/4), 61 (1986). A method of making large-area Kikuchi maps is described. Two Kikuchi maps for silicon are presented: the first one containing an area of two stereographic triangles and the second including an area around axis. As advantages of the application of Kikuchi maps to the structure defect analysis, the lack of the 180 degrees ambiguity, as well as the elimination of a time-consuming correlation of subsequent electron diffraction patterns, are emphasized. Examples of the applications, of Kikuchi maps made in a screen scale of the JEM 100B transmission electron microscope, for the determination of indices of a dislocation line direction and a Burgers vector direction as well as for the determination of grain boundary desorientation parameters, as described.
A. NEUGROSCHEL,J. NIJS and R. MERTENS.Solid-St. Electron. 30, 1143 (1987). The emitter Gummel number of bipolar transistors with an amorphous silicon emitter-base heterojunction is shown to be very large. The temperature dependence of the common-emitter current gain of such heterojunction bipolar transistors is much smaller than that of conventional homojunction transistors. With the actual technology the applicability of amorphous silicon emitters is limited by the emitter series resistance which is too high for VLSI applications. Microcrystalline silicon is a promising emitter material as it combines the high emitter efficiency of amorphous silicon emitters with a much lower resistivity, yielding lower emitter resistances.
Neuron-like transient phenomena in silicon p-i-n structures. Electronic structure of strained Si,/Ge.(O01) superlattices. S. CIRACI, O. GULSEREN and S. ELLIALTIOGLU. Solid St. Commun. 65, 1285 0988). Using the empirical tight binding method we have investigated the electronic properties of the Si,/Ge,(001) strained superlattices as a function of the superlattice periodicity and the band misfit. For n/> 4 we have found that first and second conduction band states are localized in Si. The hole states localized in Ge appear for n/> 4. The difference between the direct and indirect band gaps is reduced from 2.01 eV for bulk Si to 0.01 eV for n = 6 which can be considered to be quasi-direct. For the cases n = 6 and n = 8, the band gap might become direct for large values of band misfit.
Electrical properties of Si-SiO 2 structures treated in helium plasma. J. KASSABOV,E. ATANASSOVA,D. DIMITTROVand E. GORANOVA. Microelectron. J. 18(5), 5 (1987). Experimental data are presented for the influence of helium plasma on the electrical properties of Si-SiO2 structures with dry thermal oxide (d = 16-72nm). It is found that for strongly damaged structures low temperature helium plasma introduces acceptor-type interface states near the conduction band edge and has an annealing effect on the deep acceptortype states. It has also shown that the initial characteristics of the Si-SiO2 structures and the gas used are critical for the plasma-forming of both the interface and inversion channel properties. Optical characterization of heavily doped silicon. JOACHIM WAGNER. Solid-St. Electron. 30, 1117 (1987). Out of a variety of optical techniques used to characterize heavily doped semiconductors photoluminescence and Raman spectroscopy will be discussed as tools to study heavy doping effects. Photoluminescence spectroscopy is sensitive to electronic transitions between the conduction and valence band whereas electronic Raman scattering probes transitions within either band. Parameters relevant to device physics such as the band gap shrinkage due to heavy doping are extracted from these measurements. It is further shown that both techniques are applicable to the characterization of thin heavily doped implanted or epitaxial layers.
D. D. Coon and A. G. U. PERERA. Solid-St. Electron. 31, 851 (1988). Simulation of neuron transient phenomena by electronic processes in semiconductors is discussed from the point of view of hardware for new approaches to electronic processing of information which parallel the means by which information is processed in intelligent organisms. Neural networks in intelligent organisms are huge compared to supercomputcrs but the electrical processes are much slower because they involve ionic conduction. Recent work has uncovered a class of transient semiconductor phenomena which exhibit similarities to the way in which information is coded by neurons. The typical speed of the observed transients has been slow by the standards of electronic switching in computers. New results for such transients in silicon p-i-n structures show much faster switching times. Experimentally demonstrated features include logical operations, bifurcation, chaos and threshold behavior of firing. Further development along these lines could lead to fast, dense, neuronlike microelectronic networks that are simpler than artificial neural networks based on transistors.
Measurement of generation lifetime in thin silicon layers. T. E. HOF, T. J. MORTHORST and K. P. ROENKER.Solid-St. Electron. 31, 937 (1988). This paper describes an improved capacitance method for the measurement of the minority carrier generation lifetime in the near surface region in this silicon layers. The technique provides a simple experimental means for evaluating interferences in the leakage current, such as diffusion from the quasi-neutral bulk and peripheral generation, permitting a more accurate determination of the lifetime. Additional, related capacitance measurements are performed on adjacent circular capacitors of differing radii to quantify the extent of peripheral generation. Results are presented demonstrating application of the method and illustrating the magnitude of these interferences. These results indicate that the accurate determination of the generation lifetime in current, high quality silicon necessitates the use of experimental means, such as the technique described here, in order to quantify interference components in the leakage current. Assumptions underlying the technique and limitations in its use are discussed.
N-type SIPOS and poly-silicon emitters. Y. H. KWARKand R. M. SWANSON.Solid-St. Electron. 30, 1121 (1987). N-type SIPOS and poly-silicon emitters on silicon show potential for improved minority carrier blocking properties over conventional diffused emitters. This paper discusses experiments designed to elucidate the physical mechanisms responsible for this improvement and to optimize the process conditions. Emitters both with and without an intentionally grown chemical oxide under the SIPOS or poly-silicon film are investigated. Both poly-silicon and SIPOS emitters, in their optimized form, can achieve Jc~ of less than 2x 10-14A/cm 2, an improvement of several decades over shallow diffused emitters.
Silicon heterojunction bipolar transistors with amorphous and microcrystalline emitters. J. SYMONS, M. GnANNAM,
Heavy doping effects in silicon. ROGERJ. VAN OVERSTRAETEN and ROBERT P. MERTENS. Solid-St. Electron. 30, 1077 0987). The different mechanisms causing bandgap narrowing in heavily doped silicon are reviewed. A distinction is made between many-body effects and the effects due to random impurity distribution. The values of bandgap narrowing, calculated using a theoretical model, are compared with the experimental results. Recombination in heavily-doped silicon is discussed and the different recombination mechanisms, present at high doping levels, are explained. Experimental values for the minority-carrier lifetime as a function of the doping level are given. Surface recombination at the heavily doped Si/SiO2 interface is discussed, the transport equations in the case of a position dependent bandgap are derived, and finally the influence of
World Abstracts on Microelectronics and Reliability
Technol. 19(3/4), 61 (1986). A method of making large-area Kikuchi maps is described. Two Kikuchi maps for silicon are presented: the first one containing an area of two stereographic triangles and the second including an area around axis. As advantages of the application of Kikuchi maps to the structure defect analysis, the lack of the 180 degrees ambiguity, as well as the elimination of a time-consuming correlation of subsequent electron diffraction patterns, are emphasized. Examples of the applications, of Kikuchi maps made in a screen scale of the JEM 100B transmission electron microscope, for the determination of indices of a dislocation line direction and a Burgers vector direction as well as for the determination of grain boundary desorientation parameters, as described.
A. NEUGROSCHEL,J. NIJS and R. MERTENS.Solid-St. Electron. 30, 1143 (1987). The emitter Gummel number of bipolar transistors with an amorphous silicon emitter-base heterojunction is shown to be very large. The temperature dependence of the common-emitter current gain of such heterojunction bipolar transistors is much smaller than that of conventional homojunction transistors. With the actual technology the applicability of amorphous silicon emitters is limited by the emitter series resistance which is too high for VLSI applications. Microcrystalline silicon is a promising emitter material as it combines the high emitter efficiency of amorphous silicon emitters with a much lower resistivity, yielding lower emitter resistances.
Neuron-like transient phenomena in silicon p-i-n structures. Electronic structure of strained Si,/Ge.(O01) superlattices. S. CIRACI, O. GULSEREN and S. ELLIALTIOGLU. Solid St. Commun. 65, 1285 0988). Using the empirical tight binding method we have investigated the electronic properties of the Si,/Ge,(001) strained superlattices as a function of the superlattice periodicity and the band misfit. For n/> 4 we have found that first and second conduction band states are localized in Si. The hole states localized in Ge appear for n/> 4. The difference between the direct and indirect band gaps is reduced from 2.01 eV for bulk Si to 0.01 eV for n = 6 which can be considered to be quasi-direct. For the cases n = 6 and n = 8, the band gap might become direct for large values of band misfit.
Electrical properties of Si-SiO 2 structures treated in helium plasma. J. KASSABOV,E. ATANASSOVA,D. DIMITTROVand E. GORANOVA. Microelectron. J. 18(5), 5 (1987). Experimental data are presented for the influence of helium plasma on the electrical properties of Si-SiO2 structures with dry thermal oxide (d = 16-72nm). It is found that for strongly damaged structures low temperature helium plasma introduces acceptor-type interface states near the conduction band edge and has an annealing effect on the deep acceptortype states. It has also shown that the initial characteristics of the Si-SiO2 structures and the gas used are critical for the plasma-forming of both the interface and inversion channel properties. Optical characterization of heavily doped silicon. JOACHIM WAGNER. Solid-St. Electron. 30, 1117 (1987). Out of a variety of optical techniques used to characterize heavily doped semiconductors photoluminescence and Raman spectroscopy will be discussed as tools to study heavy doping effects. Photoluminescence spectroscopy is sensitive to electronic transitions between the conduction and valence band whereas electronic Raman scattering probes transitions within either band. Parameters relevant to device physics such as the band gap shrinkage due to heavy doping are extracted from these measurements. It is further shown that both techniques are applicable to the characterization of thin heavily doped implanted or epitaxial layers.
D. D. Coon and A. G. U. PERERA. Solid-St. Electron. 31, 851 (1988). Simulation of neuron transient phenomena by electronic processes in semiconductors is discussed from the point of view of hardware for new approaches to electronic processing of information which parallel the means by which information is processed in intelligent organisms. Neural networks in intelligent organisms are huge compared to supercomputcrs but the electrical processes are much slower because they involve ionic conduction. Recent work has uncovered a class of transient semiconductor phenomena which exhibit similarities to the way in which information is coded by neurons. The typical speed of the observed transients has been slow by the standards of electronic switching in computers. New results for such transients in silicon p-i-n structures show much faster switching times. Experimentally demonstrated features include logical operations, bifurcation, chaos and threshold behavior of firing. Further development along these lines could lead to fast, dense, neuronlike microelectronic networks that are simpler than artificial neural networks based on transistors.
Measurement of generation lifetime in thin silicon layers. T. E. HOF, T. J. MORTHORST and K. P. ROENKER.Solid-St. Electron. 31, 937 (1988). This paper describes an improved capacitance method for the measurement of the minority carrier generation lifetime in the near surface region in this silicon layers. The technique provides a simple experimental means for evaluating interferences in the leakage current, such as diffusion from the quasi-neutral bulk and peripheral generation, permitting a more accurate determination of the lifetime. Additional, related capacitance measurements are performed on adjacent circular capacitors of differing radii to quantify the extent of peripheral generation. Results are presented demonstrating application of the method and illustrating the magnitude of these interferences. These results indicate that the accurate determination of the generation lifetime in current, high quality silicon necessitates the use of experimental means, such as the technique described here, in order to quantify interference components in the leakage current. Assumptions underlying the technique and limitations in its use are discussed.
N-type SIPOS and poly-silicon emitters. Y. H. KWARKand R. M. SWANSON.Solid-St. Electron. 30, 1121 (1987). N-type SIPOS and poly-silicon emitters on silicon show potential for improved minority carrier blocking properties over conventional diffused emitters. This paper discusses experiments designed to elucidate the physical mechanisms responsible for this improvement and to optimize the process conditions. Emitters both with and without an intentionally grown chemical oxide under the SIPOS or poly-silicon film are investigated. Both poly-silicon and SIPOS emitters, in their optimized form, can achieve Jc~ of less than 2x 10-14A/cm 2, an improvement of several decades over shallow diffused emitters.
Silicon heterojunction bipolar transistors with amorphous and microcrystalline emitters. J. SYMONS, M. GnANNAM,
Heavy doping effects in silicon. ROGERJ. VAN OVERSTRAETEN and ROBERT P. MERTENS. Solid-St. Electron. 30, 1077 0987). The different mechanisms causing bandgap narrowing in heavily doped silicon are reviewed. A distinction is made between many-body effects and the effects due to random impurity distribution. The values of bandgap narrowing, calculated using a theoretical model, are compared with the experimental results. Recombination in heavily-doped silicon is discussed and the different recombination mechanisms, present at high doping levels, are explained. Experimental values for the minority-carrier lifetime as a function of the doping level are given. Surface recombination at the heavily doped Si/SiO2 interface is discussed, the transport equations in the case of a position dependent bandgap are derived, and finally the influence of