Site: Moscow Institute of Physics and Technology
Institutsky Lane, 9, Dolgoprudny
141700, Moscow Region
Fax: 7-095 576-6528
Date Visited: October 26, 1993
Report Author: C. Curtin
Dr. Evgenij Sheshin
The Moscow Institute of Physics and Technology (MIPT) was founded over fifty years ago, has about 2,000 students, and is unique in that it can select the students that attend. Students spend four years getting a basic education (i.e., the B.S. degree), then an additional one to two years specializing at a leading scientific or design institute (to obtain the M.S. degree). According to Dr. Vasenkov at the Institute of Physical and Technical Problems in Zelenograd, the students are reputed to be the best in Russia. Of the nine departments in the institute, the WTEC panelists visited the one on Physics and Quantum Electronics. In this department are three main laboratories: (1) Physics of Semiconductors, (2) Laser Physics, and (3) Problems.
Dr. Evgenij Sheshin works in the Problems Lab, where there are a total of six post-graduate students. He is studying field emission cathodes and has fifteen years of experience on emission of electrons from carbon-based materials. He believes that carbon emitters are the best candidates for practical field emission cathodes due to their self-healing characteristics, which lead to uniformity of emission (106 emission sites/fiber are possible). In addition, he believes that carbon cathodes will work at 10-6 Torr and that Spindt cathodes will need 10-8 Torr for good emission and lifetime. He has some evidence that carbon cathodes will tolerate 10-4 Torr, and that a current density of 105 A/cm2 is possible.
A life test was run to 7,000 hours with no problems. The scientists needed the equipment for another experiment, so the test was terminated. Dr. Sheshin does not have any evidence of a life failure mechanism.
Dr. Sheshin uses three types of carbon for his emitters: (1) fibers, (2) nuclear filled, and (3) polycrystalline. He is not a big fan of diamond, which has received much favorable press in the last two years, since he believes that it is much more complex than described. The Sheshin group's scientists do not fabricate their fibers, but obtain them from the Graphite Institute. They have a new method of fabricating the carbon fiber cathodes that is different than that disclosed in publications. (This method was not disclosed to the WTEC team, but Dr. Sheshin is willing to disclose it to companies interested in pursuing his technology). These emitters are being fabricated on a 30 mm x 30 mm substrate (glass CTE to match Moly), and can be operated as a single pixel or electrically connected in rows. He believes that an emitter pitch of 0.33 mm is a good design goal, and that 0.2 mm is possible. Large displays can be fabricated by tiling small substrates (20 mm x 20 mm) inside the vacuum to overcome the need for flat glass.
Field emission displays as large as 3" x 5" with 10,000 pixels, all with the same current, have been made in the past. However, WTEC panelists did not see one.
A technology demonstration was seen in a round glass enclosure (approx. 25 mm diameter) with an emission area of approx. 1 mm, bombarding the 25 mm diameter phosphor at 5 kV (i.e., a large magnification). The demonstration was quite bright, and flickering areas, possibly from individual emission sites, could be seen.
This was the only display project at MIPT, but two tools have been developed that might be of interest to researchers in vacuum microelectronics:
Due to the funding situation in Russia, all research has come to a halt at MIPT and funds are needed to further these experiments. Funds are available to cover teaching costs and salaries, but not materials or equipment for research.
Chakhovskoi, A.G. et al. 1993. "Method of Fabrication of Matrix Carbon Fiber Field Emission Cathode Structures for Flat- Panel Indicators." J. Vac. Sci. Technol. B 11(2) Mar/Apr:511-513.