Fishing – trapping – and vermin destroying
Patent
1989-02-01
1995-02-28
Hearn, Brian E.
Fishing, trapping, and vermin destroying
437176, 437179, 437126, 148DIG139, 148DIG140, H01L 2144
Patent
active
053936981
ABSTRACT:
A process for fabricating gold/gallium arsenide structures, in situ, on molecular beam epitaxially grown gallium arsenide. The resulting interface proves to be Ohmic, an unexpected result which is interpreted in terms of increased electrode interdiffusion. More importantly, the present invention surprisingly permits the fabrication of Ohmic contacts in a III-V semiconductor material at room temperature. Although it may be desireable to heat the Ohmic contact to a temperature of, for example, 200 degrees Centigrade if one wishes to further decrease the resistance of the contact, such low temperature annealing is much less likely to have any deleterious affect on the underlying substrate. The use of the term "in situ" herein, contemplates continuously maintaining an ultra-high vacuum, that is a vacuum which is at least 10.sup.-8 Torr, until after the metallization has been completed. An alternative embodiment of the present invention comprising an additional step, namely the termination of the gallium arsenide by a two monolayer thickness of epitaxial aluminum arsenide as a diffusion barrier, enables the recovery of Schottky barrier behavior, namely a rectified I-V characteristic. The present invention provides a significant breakthrough in the fabrication of III-V semiconductor devices wherein excellent Ohmic contact and Schottky barrier interfaces to such devices can be achieved simply and inexpensively and without requiring the high temperature processing of the prior art and also without requiring the use of exotic high temperature refractory materials as substitutes for those preferred contact metals such as gold, aluminum and the like.
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patent: 4908325 (1990-03-01), Berenz
Bauer et al. "Dissociative Surface reactions at Schottky and heterojunction interfaces with AlAs and GaAs", J. Vac. Sci. & Technol. vol. 19, No. 3, pp. 674-680, Sep.-Oct. 1981.
Zirath et al. "Temperature Variable Noise and Electrical characteristics of Au-GaAs Schottky Barrier Millimeter Wave Mixer Diodes", IEEE Tran. on Micr. Theo. and Techniques, vol. 36, No. 11, Nov. 1988, pp. 1469-1475.
Howes et al. "Gallium Arsenide Materials, Devices and Circuits", 1985 by John Wiley & Son, Inc., p. 195.
Bell Lloyd D.
Grunthaner Frank J.
Hecht Michael H.
Kaiser William J.
California Institute of Technology
Hearn Brian E.
Nguyen Tuan
Tachner Leonard
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