The commercial impact and benefits of this work are:
1 An operating microlens allowing to obtain a parallel or a focus deflected beam was fabricated. The design was simulated by UAM and UCBL.
2 The process of formation of the nanotip in a working environment has been systematised and this knowledge used for its deployment in a microgun environment.
3 A working UHV prototype has been developed which permits nanotip formation integrated into the mutual mechanical positioning of the nanotips and micro-lens systems for beam focusing and deflection.
4 Elaboration of a continuous process to fabricate microtips cathodes, measure their I(V) curves, treat their apex surface and make a sequence of similar experiments and observations to determine the evolution of the emitted current. Theoretical and structural studies of these field emitter microtips geometry have been performed for an optimisation of their emitted current:
- computer simulations explain the dominant secondaries emission measures in several cases. Nevertheless, the emission zone of the tip will be confined to the tip apex if the distance between the tip and the grid is about 0 nm.
- Microtips arrays present fabrication failures as low, high, off-centered or double tips formation leading to a low emission current. The higher current corresponds to a tip apex near the grid.
This study allowed to modify certain geometrical and physical parameters in order to increase the properties of microtips cathodes but also to develop a new fabrication process for silicon tips.
Electron sources based on field emission from sharp tips are central to the development of both vacuum microelectronics and miniaturised electron guns (micro-guns), both of which have potential for expanded roles in the electronics and electron microscopy industries.
The proposed research program is built around two objectives which are interdependent:
1. Basic and applied physics studies to increase the intensity, stability, brightness, coherence and reproducibility of the field emission sources of single elements and arrays.
2. Development of a miniaturised, low-voltage electron gun for its integration into an extremely compact, high resolution electron microscope.
The required principal tasks are:
- Tip treatments and formations under controlled environments of both metallic and semiconductor tips with the aim of refining and stabilising the crucial emitting apex zones of the tips. They will be performed with both nanotips, that are terminated in a nanoscale protrusion with single atom apex, and existing integrated field emitter array (FEA) devices.
- Integration of the nanotips with micron-scale electrostatic lenses and nano-displacements to develop a micro-gun. It necessarily demands the combined use of both basic physics and micro-electronic technologies. The heart of this micro-gun will be the recently developed single-atom nanotips which have extremely attractive properties as electron sources.
Funding SchemeCSC - Cost-sharing contracts