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Theoretical interpretation of Schottky barriers and ohmic contacts

Surface Science
Publication Date
DOI: 10.1016/0039-6028(86)90867-8
  • Philosophy


Abstract We review a theory of Schottky barriers that explains the following experimental findings: (i) observed barrier heights and Fermi-level pinning positions for GaAs, InP, GaSb, AlAs, GaP, InAs, and other III–V semiconductors; (ii) switching of the observed barrier heights and Fermi-level pinning positions for III–V semiconductors as a function of surface treatment or reactivity of the metal; (iii) alloy dependence of Schottky barrier heights for the ternaries Al 1− x Ga x As, GaAs 1− x P x , Ga 1− x In x P, InP 1− x As x , and In 1− x Ga x As; (iv) different slopes d E/d x for different metal contacts to AlGaAs, and an apparent cusp in the slope for Al contacts as a function of alloy composition; (v) observed Schottky barriers for a wide variety of Si/transition-metal-silicide interfaces; (vi) observed barriers for Ge, diamond, and amorphous Si; (vii) observation that Fermi-level pinning for p-GaAs disappears at the annealing temperature of the antisite defect As Ga. The theory provides a microscopic realization of the phenomenological defect model of Spicer, Lindau and coworkers. We find that most Schottky barriers are explained by dangling bonds - intrinsic dangling bonds for group IV semiconductors and antisite (as well as intrinsic) dangling bonds for III–V semiconductors. Ohmic contacts are explained in the present picture by shallow levels, which are also predicted by the theory.

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