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Self-consistent pseudopotential calculations of the equilibrium properties of bulk and surface Si
World Abstracts on Microelectronics and Reliability Moorestown speed RMA engineers from preliminary modeling to final plotted output single-handedly. The Analysis Program, with 18 mathematical models and six operating modes, handles most systems that can be represented by serially connected subsystems. The Plotting Program produces captioned block diagrams for these system analyses. Tape files hold completed analyses for plotting or editing. RECAP offers versatile options and conversational displays for user convenience. Modularity is not a matter of size. ROBERTH. DUNN and RICHARD S, ULLMAN.Proc. I EEE Reliab. Syrup., Washington, D.C., 23-25 January 1979, p. 342. Division of a computer program into a number of smaller programs designated as modules is a universally accepted practice among software engineers. A modular architecture offers the following advantages : •
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PARALLEL D E V E L O P M E N T : Defining unique sections of the program as separate entities lends itself to a work breakdown structure with task assignments parallel in time. R E D U C E D P R O G R A M SIZE AND DEVELOPMENT COST: Early recognition of similarity of seemingly disparate processes allows such operations to be isolated and programmed as common modules. UNDERSTANDABILITY: Smaller program units may be more easily understood by those responsible for subsequent program maintenance.
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RELIABILITY: Isolating various program functions in separate modules reduces the likelihood of a modification to one function inadvertently affecting other functions. TESTING: The number of discrete states possible in a portion of a program is many orders of magnitude smaller than the number possible in the whole program, thus making the testing process more manageable.
In-circuit unit does analog and digital testing. KEVIN SMITH. Electronics p. 8D (21 June 1979). ATE system does functional testing at clock rates to 5 MHz, can exercise up to 256 pins at the same time. A correlation interface circuit for microprocessor systems. J. R. JORDAN. Microelectron. J. 10, (1) 54 (1979). A prototype correlation interface circuit for use with microcomputers is described. Use of the circuit to measure system time delay from the position of the most significant peak of a correlation function is discussed. An interpolation method is described for increasing the resolution of the measurement of peak positions. A special purpose integrated circuit is proposed. Noise immunity of CMOS integrated circuits. T. CHESNEY and, R. FUNK. Microelectron. J. 10, (1) 15 (1979). Sources of noise in logic circuits are discussed and definitions stated. The good noise performance of CMOS devices is then explained.
7. SEMICONDUCTOR INTEGRATED CIRCUITS, DEVICES AND MATERIALS Retention and endurance characteristics of HCI-annealed and unannealed MNOS capacitors. W. D. BROWN. Solid-St. Electron. 22, 373 (1979). MNOS capacitors (metal-nitriteoxide-semiconductor) have been used to study the effects of memory oxide growth and post-oxidation annealing conditions on retention and endurance of MNOS devices. Results of this study indicate that write/erase cycling causes a decrease in memory window size after 105 cycles, a shift of the memory window center toward more positive values of threshold voltage, and an increase in surface state density for cycling above 106 cycles, The retention data presented indicates that the memory window decay rate for + 2 5 V writing pulses is only a function of the initial window size. The collapse of the memory window to zero volts is predicted to occur after 1016sec for native oxide devices and after 10 j 8 sec for thermal oxide devices. HC1 annealing of the memory oxide does not have a significant effect on either endurance or retention. Carrier transport across heterojunction interlaces. C. M. Wu and E. S. YANG. Solid-St. Electron. 22, 241 (1979). A general theory is presented to describe the carrier transport across heterojunction interfaces. In matching the boundary conditions at the interface, the conservation of total energy and perpendicular momentum is assumed and the difference of effective masses on two sides of the junction is taken into account. The quantum mechanical transmission coefficient is calculated by a combined numerical and WKB method. Application of the present model to an AlxGal xAs-GaAs N - n heterojunction is performed and it gives rise to rectifying characteristics together with non-saturated reverse current. Comparison with the classical thermionic emission model is made to show the significance of tunneling and effect of quantum mechanical reflection. Two dimensional electron GaAs at a semiconductor-semiconductor interface. H. L. STORMER, R. DINGLe, A. C. GOSSARD, W. W1EGMANN and M. D. STURGE. Solid St. Commun. 29, 705 (1979). We report the first observation
of a two-dimensional electron gas at a semiconductor semiconductor (GaAs-A1GaAs) interface. A novel, highmobility, persistent-photoconductive effect allows one to vary the two-dimensional carrier concentration continuously from 1.1 x 1012cm 2 to 1.6 × 1012cm 2, as obtained by Shubnikov deHaas measurements. Cyclotron resonance data establish an effective mass of 1.11 m*, where m* is the mass at the conduction-band edge of GaAs. Hall data and cyclotron resonance yield a mobility of ll ~ 5000cm2/V sec. Self-consistent psendopatential calculations of the equilibrium properties of bulk and surface Si. J. IHM and MARVIN L. COHEN. Solid St. Commun. 29, 711 (1979). A momentumspace formalism is used to study the equilibrium properties of bulk and surface Si based on the self-consistent pseudopotential method. The calculated equilibrium lattice constant and the crystal energy are in agreement with experiment. By minimizing the total energy of the system, the equilibrium relaxation for the Si (111) surface was found to be 0.15 ~, in excellent agreement with measurements on the impurity-stabilized relaxed surface, The numerical analysis of anomalous doping profiles of phosphorus in silicon. V. ARANDJELOVlC, LJ. MILKOVIC and D. TJAPKIN. Solid-St. Electron. 22, 355 (•979). The mathematical model of diffusion based on the general theory of diffusion via the vacancy mechanism has been simplified in that the vacancy distribution is approximated by its quasi-equilibrium relation. An improvement introduced into the model to improve its accuracy at very high impurity concentrations gave an increase of the calculated junction depths significant compared to the metallurgical basewidths of modern high frequency transistors. A good fit to the available experimental data has been obtained. Application of the MOSFET device structure in characterizing imperfection centers in indium-doped silicon. LEONARD FORBES, RENE BROWN, MAHMOOD SHEIKHOLESLAM and
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PARALLEL D E V E L O P M E N T : Defining unique sections of the program as separate entities lends itself to a work breakdown structure with task assignments parallel in time. R E D U C E D P R O G R A M SIZE AND DEVELOPMENT COST: Early recognition of similarity of seemingly disparate processes allows such operations to be isolated and programmed as common modules. UNDERSTANDABILITY: Smaller program units may be more easily understood by those responsible for subsequent program maintenance.
•
•
423
RELIABILITY: Isolating various program functions in separate modules reduces the likelihood of a modification to one function inadvertently affecting other functions. TESTING: The number of discrete states possible in a portion of a program is many orders of magnitude smaller than the number possible in the whole program, thus making the testing process more manageable.
In-circuit unit does analog and digital testing. KEVIN SMITH. Electronics p. 8D (21 June 1979). ATE system does functional testing at clock rates to 5 MHz, can exercise up to 256 pins at the same time. A correlation interface circuit for microprocessor systems. J. R. JORDAN. Microelectron. J. 10, (1) 54 (1979). A prototype correlation interface circuit for use with microcomputers is described. Use of the circuit to measure system time delay from the position of the most significant peak of a correlation function is discussed. An interpolation method is described for increasing the resolution of the measurement of peak positions. A special purpose integrated circuit is proposed. Noise immunity of CMOS integrated circuits. T. CHESNEY and, R. FUNK. Microelectron. J. 10, (1) 15 (1979). Sources of noise in logic circuits are discussed and definitions stated. The good noise performance of CMOS devices is then explained.
7. SEMICONDUCTOR INTEGRATED CIRCUITS, DEVICES AND MATERIALS Retention and endurance characteristics of HCI-annealed and unannealed MNOS capacitors. W. D. BROWN. Solid-St. Electron. 22, 373 (1979). MNOS capacitors (metal-nitriteoxide-semiconductor) have been used to study the effects of memory oxide growth and post-oxidation annealing conditions on retention and endurance of MNOS devices. Results of this study indicate that write/erase cycling causes a decrease in memory window size after 105 cycles, a shift of the memory window center toward more positive values of threshold voltage, and an increase in surface state density for cycling above 106 cycles, The retention data presented indicates that the memory window decay rate for + 2 5 V writing pulses is only a function of the initial window size. The collapse of the memory window to zero volts is predicted to occur after 1016sec for native oxide devices and after 10 j 8 sec for thermal oxide devices. HC1 annealing of the memory oxide does not have a significant effect on either endurance or retention. Carrier transport across heterojunction interlaces. C. M. Wu and E. S. YANG. Solid-St. Electron. 22, 241 (1979). A general theory is presented to describe the carrier transport across heterojunction interfaces. In matching the boundary conditions at the interface, the conservation of total energy and perpendicular momentum is assumed and the difference of effective masses on two sides of the junction is taken into account. The quantum mechanical transmission coefficient is calculated by a combined numerical and WKB method. Application of the present model to an AlxGal xAs-GaAs N - n heterojunction is performed and it gives rise to rectifying characteristics together with non-saturated reverse current. Comparison with the classical thermionic emission model is made to show the significance of tunneling and effect of quantum mechanical reflection. Two dimensional electron GaAs at a semiconductor-semiconductor interface. H. L. STORMER, R. DINGLe, A. C. GOSSARD, W. W1EGMANN and M. D. STURGE. Solid St. Commun. 29, 705 (1979). We report the first observation
of a two-dimensional electron gas at a semiconductor semiconductor (GaAs-A1GaAs) interface. A novel, highmobility, persistent-photoconductive effect allows one to vary the two-dimensional carrier concentration continuously from 1.1 x 1012cm 2 to 1.6 × 1012cm 2, as obtained by Shubnikov deHaas measurements. Cyclotron resonance data establish an effective mass of 1.11 m*, where m* is the mass at the conduction-band edge of GaAs. Hall data and cyclotron resonance yield a mobility of ll ~ 5000cm2/V sec. Self-consistent psendopatential calculations of the equilibrium properties of bulk and surface Si. J. IHM and MARVIN L. COHEN. Solid St. Commun. 29, 711 (1979). A momentumspace formalism is used to study the equilibrium properties of bulk and surface Si based on the self-consistent pseudopotential method. The calculated equilibrium lattice constant and the crystal energy are in agreement with experiment. By minimizing the total energy of the system, the equilibrium relaxation for the Si (111) surface was found to be 0.15 ~, in excellent agreement with measurements on the impurity-stabilized relaxed surface, The numerical analysis of anomalous doping profiles of phosphorus in silicon. V. ARANDJELOVlC, LJ. MILKOVIC and D. TJAPKIN. Solid-St. Electron. 22, 355 (•979). The mathematical model of diffusion based on the general theory of diffusion via the vacancy mechanism has been simplified in that the vacancy distribution is approximated by its quasi-equilibrium relation. An improvement introduced into the model to improve its accuracy at very high impurity concentrations gave an increase of the calculated junction depths significant compared to the metallurgical basewidths of modern high frequency transistors. A good fit to the available experimental data has been obtained. Application of the MOSFET device structure in characterizing imperfection centers in indium-doped silicon. LEONARD FORBES, RENE BROWN, MAHMOOD SHEIKHOLESLAM and