作者：
Wintner, E.Fujimoto, J.G.Ippen, E.P.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
Ultrashort light pulses are used to study carrier dynamics in highly excited semiconductor materials. Picosecond pulses from a cw modelocked Nd:YAG laser create carriers and probe nonlinear (Auger) recombination in In...
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ISBN:
(纸本)0892524871
Ultrashort light pulses are used to study carrier dynamics in highly excited semiconductor materials. Picosecond pulses from a cw modelocked Nd:YAG laser create carriers and probe nonlinear (Auger) recombination in InGaAs and InGaAsP epilayers. Femtosecond continuum pulses from a dye oscillator/amplifier system monitor the spectral dynamics of free excitons in CdSe following optical excitation.
作者：
Lewis, T.J.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
The fundamental processes of charge carrier generation and motion in pure hydrocarbon liquids under high electrical stress are reviewed in the light of present knowledge of amorphous phase electronics and of the elect...
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The fundamental processes of charge carrier generation and motion in pure hydrocarbon liquids under high electrical stress are reviewed in the light of present knowledge of amorphous phase electronics and of the electrochemistry of electrode-dielectric interfaces. The existence of quasi-free electron and equally mobile positive hole states in a liquid such as n-hexane makes it possible to develop plausible models for the extremely fast cathode and anode-initiated incipient breakdown discharge processes which have been observed. The discussion covers electronic processes in pure liquids, electrode processes, and breakdown initiation.
For the first time (In,Ga)As/InP n-p-n heterojunction bipolar transistors (HJBTs) applicable to integrated circuits have been fabricated by triple ion implantation. The base has been formed by beryllium ion implantati...
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For the first time (In,Ga)As/InP n-p-n heterojunction bipolar transistors (HJBTs) applicable to integrated circuits have been fabricated by triple ion implantation. The base has been formed by beryllium ion implantation and the collector by silicon ion implantation. The implants were made into an LPE-grown n-n (In,Ga)As/InP heterostructure on an n** plus -InP substrate. This inverted mode emitter-down heterojunction transistor structure demonstrates to a maximum current gain of 7 with no hysteresis in the characteristics. The ideality factors of the I//B versus V//B//E, and I//C versus V//B//E characteristics with V//C//B equals 0, are 1. 25 and 1. 08, respectively, indicating that the defect level in the heterojunction is low and that minority-carrier injection and diffusion is the dominant current flow mechanism.
作者：
Kuznetsov, MarkMIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
An analytic theory of well-developed pulsations in semiconductor lasers with a proton bombarded segment is presented. A rate equation model is used with the proton bombarded region modeled as a fast saturable absorber...
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An analytic theory of well-developed pulsations in semiconductor lasers with a proton bombarded segment is presented. A rate equation model is used with the proton bombarded region modeled as a fast saturable absorber. A closed-form solution is obtained for the pulse shape, width, and energy, as well as for the pulsation rate. The pulses can be as short as the diode roundtrip time (10 ps). A simple pulsation condition is derived;it agrees with the previously determined small signal instability criterion. Pulsation does not require absorber cross section larger than gain cross section.
Graded-Gate-Oxide(GGO)-MOSFETs with various degrees of gate-drain(source) overlap (and grading thickness of the gate oxide near the polysilicon-gate edge) have been investigated for hot-electron generation. Compared w...
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Graded-Gate-Oxide(GGO)-MOSFETs with various degrees of gate-drain(source) overlap (and grading thickness of the gate oxide near the polysilicon-gate edge) have been investigated for hot-electron generation. Compared with a conventional MOSFET, the GGO-MOSFET exhibits higher substrate and gate currents when the gate voltage is raised above a critical value(Vgc). Vgc is found to be dependent on the drain voltage. It is also a smooth function of the degree of gate-drain(source) overlap which can be controlled by the fabrication process. These experimental findings are supported by results obtained from the two-dimensional analysis of a similar device structure. Implications of the GGO phenomena on MOS technologies are discussed. Possible use of the GGO-MOSFET in EPROM is proposed.
Both passive and active remote sensing of atmospheric precipitation are studied with the vector radiative transfer equations by making use of the Mie scattering phase functions and incorporating the raindrop-size dist...
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Both passive and active remote sensing of atmospheric precipitation are studied with the vector radiative transfer equations by making use of the Mie scattering phase functions and incorporating the raindrop-size distributions. For passive remote sensing we employ the Gaussian quadrature method to solve for the brightness temperatures. For active remote sensing an iterative approach carrying out to the second order in albedo is used to calculate for the bistatic scattering coefficients, the backscattering cross sections/unit volume, and the interchannel cross talks. The calculated results are plotted as a function of rainfall rates and compared to various available experimental data. The theoretical model is easily applied to the remote sensing of aerosol particles, smoke, fog, and haze at infrared and visible frequencies.
作者：
Smith, Henry I.Thompson, C.V.Atwater, H.A.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
Graphoepitaxy uses artifical surface patterns to induce orientation in films. Our current graphoepitaxy research is concentrated on two low-temperature approaches that should be applicable to a wide range of material/...
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Graphoepitaxy uses artifical surface patterns to induce orientation in films. Our current graphoepitaxy research is concentrated on two low-temperature approaches that should be applicable to a wide range of material/substrate combinations and may greatly reduce orientation spread: oscillatory deposition with etchback, and surface-energy-driven secondary recrystallization of ultra-thin films.
作者：
mitter, Sanjoy K.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
Summary form only given, as follows. There appears to be intimate connections between mathematical structures and mathematical problems of physics and those of stochastic systems theory. The author discusses three sit...
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Summary form only given, as follows. There appears to be intimate connections between mathematical structures and mathematical problems of physics and those of stochastic systems theory. The author discusses three situations to illuminate these connections. The first is the relation between scattering theory (in the sense of Lax-Phillips), stochastic realization theory, and the theory of unitary dilations. In the second, an isomorphism theorem between reflection positive Gaussian processes (in the sense of Osterwalder-Schrader) and Hamiltonian systems is proved. Their relationship to Lax-Phillips scattering systems satisfying a Markov property is then discussed. The third situation is the variational principle underlying nonlinear filtering theory and its relationship to stochastic mechanics (in the sense of Nelson).
作者：
Verghese, George C.Greschak, John P.MIT
Dep of Electrical Engineering & Computer Science Cambridge MA USA MIT Dep of Electrical Engineering & Computer Science Cambridge MA USA
A generalization of the fixed-mode concept to periodically varying systems is suggested. The discrete-time version of an approach used by B. D. O. Anderson and J. B. Moore (1981) to create local observability and cont...
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A generalization of the fixed-mode concept to periodically varying systems is suggested. The discrete-time version of an approach used by B. D. O. Anderson and J. B. Moore (1981) to create local observability and controllability through the use of periodically varying decentralized output feedback is given. It is shown that this procedure actually removes fixed modes. It is suggested that 2-periodic nondynamic output feedback is generally sufficient to remove fixed modes. A range of research questions is exposed in the course of this exploration.
Preliminary results of a program to develop ion implantation confined, shallow mesa stripe (Pb,Sn)Te laser diodes are presented. The practicality of using a shallow mesa stripe to produce single mode laser output and ...
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ISBN:
(纸本)0892524731
Preliminary results of a program to develop ion implantation confined, shallow mesa stripe (Pb,Sn)Te laser diodes are presented. The practicality of using a shallow mesa stripe to produce single mode laser output and to increase the single mode tuning range are demonstrated. The first results of p-type ion implantation in the lead-tin salts are also reported. It is shown that sodium and lithium both can be used to convert n-type Pb(Te,Se) to p-type. The implant and anneal procedures are described, and electrical characteristics of Li-implanted layers are presented.
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