Origin of High-Conductivity Layer Near the Surface in As-Grown Diamond Films

Abstract

AbstractIn order to clarify the origin of p-type high-conductivity layers (HCL) near the surfaces of as-grown diamond films prepared by chemical vapor deposition, we have investigated the properties of Schottky junctions fabricated from HCL. The Schottky junctions between Al and HCL of undoped homoepitaxial films with step-flow growth showed high-rectification properties. The forward current-voltage characteristics of the junctions in the temperature range between 83 K and 400 K are found to be described by the thermionic-field emission theory. Analysis indicates that thin enough depletion layer is formed at the junction by a high concentration (∼1018/cm3) of acceptors existing in HCL due to hydrogenation. The origin of HCL is the acceptors related to incorporated hydrogen near the surface.