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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1969

Linear operation of a p-n-p-n tetrode.

Four terminal silicon planar p-n-p-n model operating as semiconductor small signal linear tetrode amplifier, discussing properties and mathematical models

Voulgaris, N. C.↗
NASA NTRS1984

Performance of the h, p and h-p versions

There are three basic versions of the finite element method, called the h, p and h-p versions. They are characterized by the way in which the finite element meshes and polynomial degree of elements are chosen. They differ in computer implementation (program architecture) and mathematical analysis. The manner in which the meshes and polynomial degree of the elements affect the accuracy of finite element solutions is examined. The approach is to fix certain parameters and increase the number of degrees of freedom so that the finie element solutions converge to the exact solution. Such a systematic increase of the number of degrees of freedom is called extension because it can be interpreted as a systematic extension of finite element spaces.

Babuska, I.↗
NASA NTRS1991

Investigation of anodic and chemical oxides grown on p-type InP with applications to surface passivation for n(+)-p solar cell fabrication

Most of the previously reported InP anodic oxides were grown on a n-type InP with applications to fabrication of MISFET structures and were described as a mixture of In2O3 and P2O5 stoichiometric compounds or nonstoichiometric phases which have properties similar to crystalline compounds In(OH)3, InPO4, and In(PO3)3. Details of the compositional change of the anodic oxides grown under different anodization conditions were previously reported. The use of P-rich oxides grown either by anodic or chemical oxidation are investigated for surface passivation of p-type InP and as a protective cap during junction formation by closed-ampoule sulfur diffusion. The investigation is based on but not limited to correlations between PL intensity and X-ray photoelectron spectroscopy (XPS) chemical composition data.

Faur, Maria↗
NASA NTRS1992

A model for the trap-assisted tunneling mechanism in diffused n-p and implanted n(+)-p HgCdTe photodiodes

A theoretical model for the trap-assisted tunneling process in diffused n-on-p and implanted n(+)-on-p HgCdTe photodiodes is presented. The model describes the traps and the trap characteristics: concentration, energy level, and capture cross sections. We have observed that the above two types of diodes differ in the voltage dependence of the trap-assisted tunneling current and dynamic resistance. Our model takes this difference into account and offers an explanation of the phenomenon. The good fit between measured and calculated DC characteristics of the photodiodes (for medium and high reverse bias and for temperatures from 65 to 140 K) supports the validity of the model.

Rosenfeld, David↗
NASA NTRS1992

A model for the trap-assisted tunneling mechanism in diffused n-p and implanted n(+)-p HgCdTe photodiodes

This paper presents a theoretical model for the trap-assisted tunneling process in diffused n-on-p and implanted n(+)-on-p HgCdTe photodiodes. The model describes the connection between the leakage current associated with the traps and the trap characteristics: concentration, energy level, and capture cross sections. It is observed that the above two types of diodes differ the voltage dependence of the trap-assisted tunneling current and dynamic resistance. The model takes this difference into account and offers an explanation of the phenomenon. The good fit between measured and calculated dc characteristics of the photodiodes supports the validity of the model.

Rosenfeld, David↗
NASA NTRS1993

Electrochemical characterization of p(+)n and n(+)p diffused InP structures

The relatively well documented and widely used electrolytes for characterization and processing of Si and GaAs-related materials and structures by electrochemical methods are of little or no use with InP because the electrolytes presently used either dissolve the surface preferentially at the defect areas or form residual oxides and introduce a large density of surface states. Using an electrolyte which was newly developed for anodic dissolution of InP, and was named the 'FAP' electrolyte, accurate characterization of InP related structures including nature and density of surface states, defect density, and net majority carrier concentration, all as functions of depth was performed. A step-by-step optimization of n(+)p and p(+)n InP structures made by thermal diffusion was done using the electrochemical techniques, and resulted in high performance homojunction InP structures.

Wilt, David M.↗
NASA NTRS1994

Increasing the yield of Ar((sup 3)P(sub 2, 0)) and Ne((sub 3)P(sub 2, 0)) effusing from a glow discharge by using a longitudinal magnetic field

It is demonstrated that a longitudinal magnetic field applied to a low-pressure, low-voltage, hot cathode glow discharge will substantially increase the intensity of metastable atoms effusing from a central anode slit. For an argon discharge there is a fourfold increase in the effusing Ar((sup 3)P(sub 2, 0)) atom intensity and for neon there is a 14-fold increase in Ne((sup 3)P(sub 2, 0)) intensity.

Barrios, A.↗
NASA NTRS1996

Electron Impact Excitation of Autoionizing Levels of Kr and Xe Between the (sup 2)P(sub 3/2) and (sup 2)P(sub 1/2) Ionic Limits

We have observed electrons ejected from autoionizing levels which lie between the (sup 2)P(sub 3/2) and (sup 2)P(sub 1/2) ionic limits for Kr and Xe. Kinetic energy spectra of the ejected electrons were obtained following electron impact excitation of the target gases by using time-of-flight spectroscopy in a crossed beam experiment. Spectral features which correspond to electrons ejected from both odd and even parity autoionizing levels have been identified.

autoionizing ejected electrons↗