Field emission and stability

In the recent years the interest in sub-micron and nano-electromechanical systems (NEMS) has grown significantly. Compared to micro-scale systems, nano-structures have higher sensitivity, lower power consumption and better mechanical characteristics. Traditional resistive and capacitive displacement detection techniques fail at nano-scale dimensions. External optical interferometry or magnetomotive techniques are used to readout the deflection of a nano-scale cantilever. [1] An alternative sensing method which can be suitable for nano-scale dimensions is field emission. With this technique the field emission current is used to measures displacements between two conducting materials. The exponential relation between the emission current and the distance makes it an accurate and very sensitive sensor for small displacements. For practical applications the unstable behavior of the field emission is the limiting factor and will greatly reduce the sensitivity and reproducibility of themeasurements. Field emission sensing has been used in previous studies in pressure sensors [2], cantilever sensors [1] and positioning [3].