Electric field dependence of GaAs Schottky barriers

Abstract

The bias dependence of the photoelectric barrier energy of n-GaAs-Al diodes has been measured. The devices were fabricated by cleavage of the GaAs in an evaporating stream of metal in a vacuum of 10^(−8) torr. The barrier energies at various bias levels were determined by extrapolation of the photoresponse vs. photon energy plots. The electric field dependence of the photoresponse was also measured at constant photon energy. The calculated change in barrier energy from the latter method was then compared with the changes in extrapolated values of barrier energy. A small systematic disagreement was observed and attributed to the effects of collection efficiency in the GaAs. The field dependence of Schottky barriers on 5×10^(16) GaAs was found to be in good agreement with that expected from the exponential charge distribution associated with the surface states which determine the barrier energy.

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