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Auger and radiative recombination of acceptor bound excitons in semiconductors
World Abstracts on Microelectronics and Reliability recombination enhanced reaction kinetics is discussed conceptually. Implications concerning the structural and chemical nature of host materials, recombination centers and reactant products is outlined. The role of recombination enhanced phenomena in device degradation is discussed and some useful applications of REDR in the selective programming of logic arrays and high definition electron beam data storage are presented.
Electron-hole droplet condensation in semiconductors; phase diagrams. T. L. REINECKEand S. C. YING. Solid-St. Electro,. 21, 1385 (1978). The shape of the phase diagrams for electron-hole droplet condensation in semiconductors is discussed using a non-interacting droplet fluctuation model. From measurements of the shape of such phase diagrams in the region T > ½T,, estimates of the droplet surface tension can be obtained, and from microscopic calculations of the surface tension theoretical phase diagrams can be constructed. The model provides a simple method to characterize quantitatively the shape of the diagram. An approximate "scaling rule" involving the ratio of the droplet ground state energy ~;~jand the critical temperature T,. is suggested. It is suggested that the shape of the phase diagram is expected to depend somewhat on details of the droplet energetics in particular semiconductor systems.
Anisotropic phonon generation in GaAs epilayers and pn junctions. V. NARAYANAMURTI,R. A. LOGAN,M. A. CHIN and M. LAX. Solid-St. Electron. 21, 1295 (1978). Phonon generation in n-GaAs epilayers and pn junctions is studied by means of a superconducting bolometer and time of flight techniques. Phonon emission is found to depend markedly on propagation direction, carrier concentration and defect density. Results obtained with n-layers are compared to theoretical estimates of the generation rate due to screened piezoelectric and deformation potential interactions. The data provide a vivid demonstration of theoretical selection rules.
Auger and radiative recombination of acceptor bound excitons in semiconductors. G. C. OSBOURN, S. A. LYON, K. R. ELLIOTT, D. L. SMITH and T. C. McGILL. Solid-St. Electron. 21, 1339 (1978). We report on a theoretical and experimental study of acceptor bound exciton recombination. We present calculations of phononless Auger and radiative recombination in direct and indirect band gap materials. We consider hydrogenic acceptors in the direct band gap material Hg~ ~Cd~Te in which the band gap can be varied by changing alloy composition. We present calculations of the Auger transition rate and no-phonon oscillator strengths for the common acceptors in Si and Ge. We have measured the bound exciton lifetimes and no-phonon oscillator strengths for the acceptors in Si and find reasonable agreement with the calculated values.
Computer analysis of punch-through in MOSFETs. N. KOTANI and S. KAWAZU. Solid-St. Electron. 22, 63 (1979). A two-dimensional numerical analysis is made for MOSFETs having short channel lengths. The short channel MOSFET is especially characterized by the existence of 8. T H I C K -
AND
THIN-FILM
COMPONENTS,
Time dependence of ion-migration effects in NiCr resistor films. U. SMITHand R. HOFFMANN.Electrocomp. Sci. Technol. 5, 159 (t 978). This paper reports the effects of ion-migration on NiCr-resistor films sputtered on the substrates Corning 0211 and 7059. Graphs showing the influence of magnitude and polarity of the bias potential, of the separation between resistor and counter-electrode, and of reversal of bias polarity are given for Corning 0211 substrates at a temperature of 100°C and in a relative humidity of 0.7~/,, for periods
199
the punch-through current which cannot be explained by the one-dimensional MOSFET models. The twodimensional analysis makes clear the following facts relating about the punch-through mechanism. The punchthrough is a condition in which the depletion layers of the source and the drain connect mutually at the deep region in the substrate even in equilibrium. The punchthrough current is injected through the saddle point of the intrinsic potential into the drain region by the electric field from the drain, at the low gate voltages.
Diffusion coefficient of hot electrons in GaAs. J. POZELA and A. REKLArrls. Solid St. Commun. 27, 1073 (1978). The longitudinal and transverse diffusion coefficient of hot electrons in GaAs at a lattice temperature of 300K has been calculated by the Monte Carlo technique. The calculations showed that drift velocity and diffusion coefficient of hot electrons in GaAs can be fitted to available experimental data if the three-valley F L X model is used. The estimates of some parameter values of GaAs conduction band have been made. A cluster plus effective medium tight-binding study of SiOx systems. M. LANNOO and G. ALLAN. Solid St. Commun. 28, 733 (t978). The valence band density of states of s i n x amorphous systems is calculated using a tight-binding treatment. The Green's function method is applied to a small cluster embeddied in a suitable effective medium. An average of this Green's function is then performed assuming a statistical distribution of composition for the small clusters. The effective medium is treated as a Bethe lattice of the correct composition. The results are completely consistent with experiment if the s i n Si angle is assumed to decrease with x.
Observations of dislocations and junction irregularities in bipolar transistors using the E.B.LC. mode of the scanning electron microscope. P. ASHBURN and C. J. BULL. Solid-St. Electron. 22, 105 (1979). The E.B.I.C. mode of the SEM has been used to study defect structures in bipolar transistors, with particular attention paid to the way in which the presence of the second junction affects the contrast. When the E.B.1.C. signal was collected from the emitter/ base junction. However, when the signal was collected from the collector/base junction, black contrast was observed for an open-circuit emitter/base junction and white contrast for a short-circuit junction. It is shown that the white contrast is caused by irregularities in the emitter/base junction, resulting from a local retardation of the phosphorus diffusion at points where dislocations occur.
Numerical analysis of electric semiconductor structures. S. RITZ, R. GOTZE and R. SCHUFFNY. Nachrichtentechnik Elektronik 28, (12) 501 (1978). (In German.) The mathematical physical model of electronic semiconductor structures and the principle of numerical methods of solving basic semiconductor equations are discussed. Moreover, results are given of the static and dynamic analysis of a p - n structure and a Gunn diode in the high-field dipole mode.
HYBRID
CIRCUITS
AND
MATERIALS
of time ranging up to 1000 hours. Results for resistors having a NiCr-oxide layer between the film and the Coming 0211 substrate as well as for NiCr resistors on Corning 7059 substrate are also presented. Previous use of a biaselectrode at positive potential is shown to lead to a depletionrecovery effect. The physical interpretation of the experimental features is given in terms of a model involving anodic oxidation at the positive electrode and formation of a low conductivity deposit at the negative electrode.
Electron-hole droplet condensation in semiconductors; phase diagrams. T. L. REINECKEand S. C. YING. Solid-St. Electro,. 21, 1385 (1978). The shape of the phase diagrams for electron-hole droplet condensation in semiconductors is discussed using a non-interacting droplet fluctuation model. From measurements of the shape of such phase diagrams in the region T > ½T,, estimates of the droplet surface tension can be obtained, and from microscopic calculations of the surface tension theoretical phase diagrams can be constructed. The model provides a simple method to characterize quantitatively the shape of the diagram. An approximate "scaling rule" involving the ratio of the droplet ground state energy ~;~jand the critical temperature T,. is suggested. It is suggested that the shape of the phase diagram is expected to depend somewhat on details of the droplet energetics in particular semiconductor systems.
Anisotropic phonon generation in GaAs epilayers and pn junctions. V. NARAYANAMURTI,R. A. LOGAN,M. A. CHIN and M. LAX. Solid-St. Electron. 21, 1295 (1978). Phonon generation in n-GaAs epilayers and pn junctions is studied by means of a superconducting bolometer and time of flight techniques. Phonon emission is found to depend markedly on propagation direction, carrier concentration and defect density. Results obtained with n-layers are compared to theoretical estimates of the generation rate due to screened piezoelectric and deformation potential interactions. The data provide a vivid demonstration of theoretical selection rules.
Auger and radiative recombination of acceptor bound excitons in semiconductors. G. C. OSBOURN, S. A. LYON, K. R. ELLIOTT, D. L. SMITH and T. C. McGILL. Solid-St. Electron. 21, 1339 (1978). We report on a theoretical and experimental study of acceptor bound exciton recombination. We present calculations of phononless Auger and radiative recombination in direct and indirect band gap materials. We consider hydrogenic acceptors in the direct band gap material Hg~ ~Cd~Te in which the band gap can be varied by changing alloy composition. We present calculations of the Auger transition rate and no-phonon oscillator strengths for the common acceptors in Si and Ge. We have measured the bound exciton lifetimes and no-phonon oscillator strengths for the acceptors in Si and find reasonable agreement with the calculated values.
Computer analysis of punch-through in MOSFETs. N. KOTANI and S. KAWAZU. Solid-St. Electron. 22, 63 (1979). A two-dimensional numerical analysis is made for MOSFETs having short channel lengths. The short channel MOSFET is especially characterized by the existence of 8. T H I C K -
AND
THIN-FILM
COMPONENTS,
Time dependence of ion-migration effects in NiCr resistor films. U. SMITHand R. HOFFMANN.Electrocomp. Sci. Technol. 5, 159 (t 978). This paper reports the effects of ion-migration on NiCr-resistor films sputtered on the substrates Corning 0211 and 7059. Graphs showing the influence of magnitude and polarity of the bias potential, of the separation between resistor and counter-electrode, and of reversal of bias polarity are given for Corning 0211 substrates at a temperature of 100°C and in a relative humidity of 0.7~/,, for periods
199
the punch-through current which cannot be explained by the one-dimensional MOSFET models. The twodimensional analysis makes clear the following facts relating about the punch-through mechanism. The punchthrough is a condition in which the depletion layers of the source and the drain connect mutually at the deep region in the substrate even in equilibrium. The punchthrough current is injected through the saddle point of the intrinsic potential into the drain region by the electric field from the drain, at the low gate voltages.
Diffusion coefficient of hot electrons in GaAs. J. POZELA and A. REKLArrls. Solid St. Commun. 27, 1073 (1978). The longitudinal and transverse diffusion coefficient of hot electrons in GaAs at a lattice temperature of 300K has been calculated by the Monte Carlo technique. The calculations showed that drift velocity and diffusion coefficient of hot electrons in GaAs can be fitted to available experimental data if the three-valley F L X model is used. The estimates of some parameter values of GaAs conduction band have been made. A cluster plus effective medium tight-binding study of SiOx systems. M. LANNOO and G. ALLAN. Solid St. Commun. 28, 733 (t978). The valence band density of states of s i n x amorphous systems is calculated using a tight-binding treatment. The Green's function method is applied to a small cluster embeddied in a suitable effective medium. An average of this Green's function is then performed assuming a statistical distribution of composition for the small clusters. The effective medium is treated as a Bethe lattice of the correct composition. The results are completely consistent with experiment if the s i n Si angle is assumed to decrease with x.
Observations of dislocations and junction irregularities in bipolar transistors using the E.B.LC. mode of the scanning electron microscope. P. ASHBURN and C. J. BULL. Solid-St. Electron. 22, 105 (1979). The E.B.I.C. mode of the SEM has been used to study defect structures in bipolar transistors, with particular attention paid to the way in which the presence of the second junction affects the contrast. When the E.B.1.C. signal was collected from the emitter/ base junction. However, when the signal was collected from the collector/base junction, black contrast was observed for an open-circuit emitter/base junction and white contrast for a short-circuit junction. It is shown that the white contrast is caused by irregularities in the emitter/base junction, resulting from a local retardation of the phosphorus diffusion at points where dislocations occur.
Numerical analysis of electric semiconductor structures. S. RITZ, R. GOTZE and R. SCHUFFNY. Nachrichtentechnik Elektronik 28, (12) 501 (1978). (In German.) The mathematical physical model of electronic semiconductor structures and the principle of numerical methods of solving basic semiconductor equations are discussed. Moreover, results are given of the static and dynamic analysis of a p - n structure and a Gunn diode in the high-field dipole mode.
HYBRID
CIRCUITS
AND
MATERIALS
of time ranging up to 1000 hours. Results for resistors having a NiCr-oxide layer between the film and the Coming 0211 substrate as well as for NiCr resistors on Corning 7059 substrate are also presented. Previous use of a biaselectrode at positive potential is shown to lead to a depletionrecovery effect. The physical interpretation of the experimental features is given in terms of a model involving anodic oxidation at the positive electrode and formation of a low conductivity deposit at the negative electrode.