Room-Temperature Negative Differential Resistance in Amorphous Carbon: The Role of Electron Trapping Defects at Device Interfaces

Abstract

Hysteresis and NDR have been observed in the room-temperature current–voltage characteristics of lateral devices featuring planar graphitic electrodes separated by a nitrogen-doped amorphous carbon (a-CN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> ) layer. The devices were fabricated using energetic physical vapor deposition and electron-beam lithography. Devices formed on a-CN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> layers deposited with N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> pressure of 0.10 mTorr exhibited NDR. This NDR occurred at a well-defined voltage/electric field but only after the voltage of the opposite polarity was applied. Based on this behavior, a model is proposed in which the NDR occurs by field-induced trapping/detrapping at one of the graphite/a-CN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> interfaces within the device. The results of this investigation highlight the importance of interfaces and defects in determining the characteristics of a-C memristive devices.