Barrier Height of Metal/InP Schottky Contacts with Interface Oxide Layer

Abstract

The barrier height q φ B for metal/InP Schottky contacts with an interface oxide layer formed by exposing an InP surface to microwave-induced oxygen radicals has been studied as a function of metal work function q φ m · q φ Bn ( q φ Bp ) for n (p)-type InP contact is found to increase (decrease) linearly with increasing q φ m for a fixed oxide layer thickness. Sum of q φ Bn and q φ Bp for each metal is found to roughly coincide with the band gap of InP. Based on the interface layer theory which considers fixed charges at the interface between the oxide layer and the semiconductor, the dielectric constant for the oxide layer ε i of ∼6ε 0 , the interface state density D s of ∼2×10 13 eV -1 ·cm -2 and the positive interface fixed charge density Q s / q of ∼5×10 12 cm -2 have been evaluated, indicating that the volume charge within the oxide layer is negative.