Investigating the properties of interfacial layers in planar Schottky contacts on hydrogen-terminated diamond through direct current/small-signal characterization and radial line small-signal modelling

Large-area Schottky diodes on hydrogen-terminated diamond are investigated through DC and small-signal characterization and physics-based equivalent circuit modeling. Measured current- and capacitance-voltage characteristics suggest significant distributed resistance effects induced by the relatively low mobility of the 2D hole gas in the diamond sub-surface. A distributed equivalent circuit model of the device is proposed aimed at correlating the device physics with the observed electrical behavior. It is shown that a heterostructure-like model of H-diamond Schottky contacts, including a thin non-conductive interfacial layer that separates the 2D hole channel from the Schottky barrier, enables an accurate description of both the device DC and AC behaviour and the extraction of relevant quantitative information on the physical parameters of the interface, channel charge control and carrier mobility.