IV.15 - Electron-Emitting Diodes?

from Paul Woods (paulw@hpcvnq08.cv.hp.com) at HP:

Have you heard of electron-emitting diodes? They are not readily available, in fact, I have only seen two or three references to them in physics literature. The most notable reference was in Philips Technical Review in 1987. Two researchers had made a diode with a very thin, heavily doped n-layer. When the diode was reverse-biased to the point of avalanche breakdown, a small fraction of the avalache electrons actually shot through the n-region and into a vacuum. They made this the e-beam source in a CRT and it worked pretty well. I am surprised that it has not, to my knowledge, made it out of the laboratory. It did have some unique requirements that probably made it expensive to produce. For one thing, the doping profile was very abrupt and required MBE which is slow and expensive. Also, to improve emission efficiency they reduced the surface work function by coating the emitting surface with Cs. I have heard that Cs is nasty to work with.

Curious things, aren't they? Sounds like a good thesis for someone. Perhaps they could be made practical using rapid thermal CVD instead of MBE.

Since nobody makes them commercially, here are some references instead:

• van Gorkom, G. G. P., and A. M. E. Hoeberechts. "Silicon Cold Cathodes", Philips Technical Review, vol. 43, no. 3, Jan. 1987.
• van Zutphen, Tom. "Development of a GaAs Avalanche Electron-Emitting Diode Cold-Electron Emitter", IEEE Transactions on Electron Devices, vol. 36, no. 11, Nov. 1989.
• Bartelink, D. J., et al. "Hot-Electron Emission from Shallow p-n Junctions in Silicon", Physical Review, vol. 110, no. 3, May 1963.
• Higman, J. M., et al. "Monte Carlo Simulation of Si and GaAs Avalache Electron Emitting Diodes", J. Appl. Phys. 65(3), Feb 1989.