Development of single electron field emitters based on tailor-made semiconducting nanowire arrays for THz sources

Domain topic

Nano Physics



The aim of this project is to realize a new class of tunable field emitter arrays based on semiconductor nanowires, which we coined as FEANs. Mastering the flow and the emission of single electrons from arrays of nanowire contacts would open a new chapter of the physics of field emission. In particular we are aiming at designing, fabricating, and employing large-scale field emitter arrays consisting of precisely grown nanowires (NWs). The strength of this approach is that we will be able to emit one electron per cycle with the emission of all NWs being correlated. This triggered, collective emission of single electrons from a large array holds the essential promise of an ultimately precise yet applicable electron source for THz-technology.

Project Description

With our advanced processing technology we have the ability to pattern large-scale wafers (up to 6’’) with a resolution down to 8nm. This can be performed by electron-beam-lithography (EBL) stitching free over an entire wafer. These predefined arrays with 10nm dots form the seedlings for a subsequent MOCVD growth step. With the help of our collaborators at Lund University we are then able to define the NWs. These growth techniques allow for atomic layer precision growth. Hence, we can define entire quantum wells inside the NWs. At diameters below 50nm we can rely on the Coulomb repulsion of electrons passing through the NWs and finally leaving the NWs via field emission. The exact layer sequence for the NWs will defined based on finite element analyses/simulations: In principle the NW length is maximized to enhance the electric field enhancement. Here the diameter is so small that the mechanism of Coulomb blockade controls the charge transfer one-by-one. The inset illustrates the circuit diagram for a single NW of the entire FEAN. The dominating element is the charged island on top of the NW and its capacitance towards vacuum. There are several experimental key points we have to control: (i) The Coulomb-controlled field emission from a single NW; (ii) Interaction of the NWs within the array yielding collective field emission of single electrons; (iii) Materials concerns, migration, current density.

Methodological keywords

Electrodynamics, propagation methods, assembly and calibration, stochastic processes and noise