The effect of the periphery of metal-semiconductor Schottky-barrier contacts on their electrical characteristics

Abstract

During the formation of the metal-semiconductor contact with a Schottky barrier (as a gold film on the p- or n-type gallium arsenide surface), an electric field E l built into the electric contact is induced, which propagates around the contact to the distance l (halo) tens of times larger than space-charge region sizes. This field reduces the electrostatic potential of the φAu contact by a significant value φ*. In the general case, the halo size l and the decrease φ* in the electrostatic potential are controlled by the charge value and sign in the space-charge region, which depend on the contact diameter D, semiconductor concentration and conductivity type. For Au/n-GaAs Schottky-barrier contacts, a decrease in D results in the increasing role of periphery, which manifests itself in increasing φ* and decreasing φAu and l. For Au/p-GaAs contacts, a decrease in D results in the decreasing effect of periphery, which appears in decreasing φ* and increasing φAu and l. The absence of the space-charge region in metal-insulator-semiconductor contacts results in the fact that the halo size l and φ* are independent of their diameters.