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

Abstract

The barrier height qφB 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 qφm·qφBn (qφBp) for n (p)-type InP contact is found to increase (decrease) linearly with increasing qφm for a fixed oxide layer thickness. Sum of qφBn and qφBp 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 εi of ∼6ε0, the interface state density Ds of ∼2×1013 eV-1·cm-2 and the positive interface fixed charge density Qs/q of ∼5×1012 cm-2 have been evaluated, indicating that the volume charge within the oxide layer is negative.