Engineering topics

Anderson, W. T., Jr.

Publications and source records attributed to Anderson, W. T., Jr..

3 records

NASA NTRS1981

Ohmic contacts to GaAs for high-temperature device applications

Ohmic contacts to n-type GaAs were developed for high temperature device applications up to 300 C. Refractory metallizations were used with epitaxial Ge layers to form the contacts: TiW/Ge/GaAs, Ta/Ge/GaAs, Mo/Ge/GaAs, and Ni/Ge/GaAs. Contacts with high dose Si or Se ion implantation of the Ge/GaAs interface were also investigated. The contacts were fabricated on epitaxial GaAs layer grown on N+ or semi-insulating GaAs substrates. Ohmic contact was formed by both thermal annealing (at temperatures up to 700 C) and laser annealing (pulsed Ruby). Examination of the Ge/GaAs interface revealed Ge migration into GaAs to form an N+ doping layer. The specific contact resistances of specimens annealed by both methods are given.

Anderson, W. T., Jr.↗

NASA NTRS1975

Superconducting properties of Pb-Sn-In alloys directionally solidified aboard Skylab

Superconducting alloys of Pb-Sn-In were directionally solidified in the absence of gravity-induced convection and segregation by processing in a near weightless condition aboard Skylab. Lead-rich and tin-rich lamellar structures were obtained with both high and low G/R (temperature gradient/solidification rate) samples processed at 0-g and at 1-g in a ground-based laboratory. Thinner, higher density lamellae were found with the 0-g specimens. Magnetization curves at 4.2 K showed hysteresis effects with large areas under the curves indicating magnetic flux pinning by the normal state tin-rich phase.

Anderson, W. T., Jr.↗

NASA NTRS1974

Space processing applications payload equipment study. Volume 2A: Experiment requirements

An analysis of the space processing applications payload equipment was conducted. The primary objective was to perform a review and an update of the space processing activity research equipment requirements and specifications that were derived in the first study. The analysis is based on the six major experimental classes of: (1) biological applications, (2) chemical processes in fluids, (3) crystal growth, (4) glass technology, (5) metallurgical processes, and (6) physical processes in fluids. Tables of data are prepared to show the functional requirements for the areas of investigation.

Smith, A. G.↗