Electrical characterization of Schottky diodes based on boron doped homoepitaxial diamond films by conducting probe atomic force microscopy

A large planar tungsten carbide (WC) Schottky diode on p-type homoepitaxial diamond was mainly investigated on a microscopic level by atomic force microscopy (AFM) and conducting probe atomic force microscopy (CP-AFM), allowing simultaneous topographic and local electrical resistance imaging measurements. These techniques revealed the existence of a specific microstructure on the WC Schottky contact consisting of electrically insulating islands surrounded by conductive paths. The islands are found to be insulating in the whole range of explored bias [-5 V, +5 V], whereas the current flowing between the islands is 1000 times lower at a reverse bias of -5 V than at a forward bias of +5 V, in agreement with the rectifying ratio found from macroscopic current-voltage (I-V) measurements. CP-AFM provides a prospective imaging tool which is well suited for analyzing the local electrical properties and instabilities of Schottky junctions. (c) 2006 Elsevier Ltd. All rights reserved.