Elsevier

Thin Solid Films

Volume 123, Issue 1, 4 January 1985, Pages 1-8
Thin Solid Films

Degradations in the electrical and structural characteristics of Schottky diodes and ohmic contacts to GaAs due to thermal aging

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Abstract

The reliability of GaAs microwave devices is directly related to the integrity of Schottky and ohmic contacts for Schottky barrier devices and metal/semiconductor field effect transistor devices. The interface analysis of these device structures using surface analysis techniques has become extremely important in the study of the degradation of these devices. The research reported here focuses on three different metallic systems, namely Au/In, Au-12 wt.% Ge and Ni/AuGe, for both Schottky and ohmic contacts. The three metallic systems were evaporated onto 〈100;〉- oriented GaAs substrates (ND=3×1017cm-3) in an ultrahigh vacuum system. These samples were thermally aged by keeping them at 150°C for 500h. Current-voltage and capacitance-voltage measurements were made on as-deposited and thermally aged samples. The ideality factor decreased in all the samples. There was an apparent large increase in barrier height in AuGe/GaAs and Ni/AuGe/GaAs Schottky diodes. There was an insignificant change in the contact resistivity of ohmic contacts after thermal aging.

The changes in the electrical characteristics of these device structures are explained on the basis of the formation of an oxide layer after thermal aging. A comparison of the Auger depth profiles of the as-deposited and the thermally aged samples substantiates the electrical observations. However, Au/In/GaAs Schottky diodes do not show the existence of an oxide layer at the interface. The out-diffusion of indium to the surface might have removed the oxygen from the interface to result in an Au-GaAs interface in the thermally aged sample. A slight increase in the barrier height of this sample is due to the Au-GaAs interface rather than the In-GaAs interface.

References (10)

  • A.K. Kulkarni et al.

    Thin Solid Films

    (1982)
  • E. Kuphal

    Solid-State Electron.

    (1981)
  • R.C. Eden et al.

    IEEE Spectrum

    (December 1983)
There are more references available in the full text version of this article.

Cited by (6)

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  • Degradation of GaAs/AlGaAs quantized hall resistors with alloyed AuGe/Ni contacts

    1998, Journal of Research of the National Institute of Standards and Technology
  • Annealing studies on Pd/n-GaAs Schottky diodes

    1991, Semiconductor Science and Technology

Paper presented at the International Conference on Metallurgical Coatings, San Diego, CA, U.S.A., April 9–13, 1984.

Present address: Hughes Aircraft Torrance Research Center, Mail Stop 2006, P.O. Box 2999, Torrance, CA 90509, U.S.A.

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