Nanoscale Field-Emission Frequency Mixer

In the first half of the twentieth century, all electronic devices used vacuum tubes in their circuits. However, the emergence of the transistor and later integrated circuit (IC) technology, quickly replaced the bulky vacuum tubes in almost all areas. Solid-state electronics (SSE) devices were less fragile, smaller, more energy efficient, and above all, able to be mass-produced. Thus, vacuum devices were displaced to a handful of niche applications such as microwave power amplifiers, and high temperature and radiation environments. Yet, despite the apparent pushover of SSE, vacuum technology did not perish. Paradoxically, the same fabrication and processing tools developed to shrink the size of solid-state ICs also enabled the miniaturization of vacuum technology giving rise to the field of vacuum nanoelectronics. By reducing their physical dimensions, vacuum devices can leverage some of the distinct inherent advantages including ballistic electron transport due to the lack of lattice scattering as well as resilience in harsh environments. The re-emergence of this technology is opportune as SSE seem to be approaching their technical limitations, as heat dissipation and quantum effects are arising due to the steady shrinkage.

In this work we will describe the fabrication of planar nanoscale multi-tip vacuum field emission devices for frequency conversion. These devices operate via Fowler-Nordheim emission, namely the quantum mechanical tunneling of electrons through the surface potential barrier by means of a high electrostatic field. By virtue of a planar geometry that minimizes the overlapping area between the electrical terminals, very low capacitance can be achieved for fast operation. Preliminary results to lower the emitter work function and enchance emission current will also be discussed.