Negative differential conductance observed in electron field emission from band gap modulated amorphous-carbon nanolayers

Amorphous-carbon (a-C)-based quantum confined structures were synthesized by pulsed laser deposition. In these structures, electrons are confined in a few nanometer thick sp2 rich a-C layer, which is bound by the vacuum barrier and a 3nm thick sp3 rich a-C base layer. In these structures anomalous field emission properties, including negative differential conductance and repeatable switching effects, are observed when compared to control samples. These properties will be discussed in terms of resonant tunneling and are of great interest in the generation and amplification of high-frequency signals for vacuum microelectronics and fast switching devices.