Measuring spatial distribution of electron emission by use of a dye that changes color when hit by electrons 

Contacts:

Gunver Nielsen, CINF, DTU Physics, PhD student (gunver.nielsen@fysik.dtu.dk)
Lasse B. Thomsen, CINF, DTU Physics, PhD student (lasse.thomsen@fysik.dtu.dk)
Robert Jensen, CINF, DTU Physics, PhD student (Robert.jensen@fysik.dtu.dk
Ib Chorkendorff, CINF, DTU Physics, 4525-3170 (ibchork@fysik.dtu.dk)

http://www.cinf.dtu.dk/~s001610

Upper: Hot Electrons are tunneling into both the elements in the array of hot electron emitters. Lower: The oxide under the right element is broken down and the increased current has led the two nano-fuses to disconnect the connection to the rest of the array to avoid drawing excess current through the array.

At CINF we are working with hot electron devices, which are Si-SiO₂-Metal sandwiches which are capable of emitting electrons either into the top metal film or into the vacuum. The electrons are emitted by setting a bias between the Si-layer and the metal layer which causes electrons to tunnel through the SiO₂ -layer. When emitting electrons into the vacuum, some spatial distribution of the emittance is unavoidable due to both small impurities in the device and to the finite electrical resistance of the metal film which causes a voltage drop across the film and thus a gradient in the intensity of electrons.

In this project, we would like to you to characterize the spatial distribution of the electrons by using a special dye (a colored substance) that changes color when hit by electrons. You will investigate how homogeneous the emittance is, and also how it depends on the oxide thickness and the top metal layer. Further you will investigate the spatial resolution of the dye, ie. how small features will we be able to resolve using the dye? Also, we would like to learn how the dye reacts to electrons; eq. how many electrons does it take to change the color? Will the dye react differently to electrons of different energy?