Structural model of III–V compound semiconductor Schottky barriers

Abstract

Schottky barriers have been fabricated on n-type GaP(111) crystals to study the structural characteristics of the diodes. The formation of Schottky barriers by evaporating a metal layer onto the III–V compound semiconductor surface generally created an amorphous film interlayer between the metal and the semiconductor. Current–voltage (I–V), capacitance–voltage (C–V) and Auger electron spectroscopy (AES) data were used to characterize the interface amorphous film. A model of a resistor in parallel with a capacitor and then in series with the metal and the semiconductor layers is used to describe the properties of a real Schottky barrier. The thickness of the amorphous film is in the range 50–500 Å, dependent on evaporation details. The dielectric constant and the resistivity of the amorphous film are experimentally estimated, and are found to be frequency dependent. A metal-amorphous film–semiconductor (MAS) configuration is proposed to be the structural model for a real Schottky barrier. The structural model is combined with the defect model to explain the fundamental transition in interface electronic nature between covalent and ionic semiconductors as well as other properties of a real Schottky barrier.