Site: Russian Academy of Sciences
Institute of Crystallography
Moscow 117333
Russia

Date Visited: October 26, 1993

Report Author: R.R. Rice

ATTENDEES

WTEC:

P.E. Cladis
R.R. Rice
D. Slobodin
J. Talbot

HOSTS:

Dr. Eugene I. Givargizov

Head of Laboratory

BACKGROUND

The Institute of Crystallography is operated by the Russian Academy of Sciences. The institute operates about thirty laboratories, of which ten are devoted to crystal growth. Only one was used for epitaxial film growth. The institute maintains equipment for crystal evaluation, including X-ray diffraction, SEM, TEM, field ion microscopy, and field emission characterization. The institute was considering adding an STM capability. The total staff of the institute, which had experienced some reductions, was a few hundred.

RESEARCH AND DEVELOPMENT ACTIVITIES

The activities in semiconducting materials were primarily centered on silicon and silicon film growth. Work was being performed in patterned growth from the vapor phase, and some laser-assisted growth had been attempted. There was really no work underway to support advanced semiconductor device technology as such. Some interesting work in a silicon-on-oxidized silicon was underway with an intent to demonstrate 3-D circuits.

Recently [Oct. '94 information - ed.] some work on active matrix LCDs has been undertaken. Amorphous Silicon films on glass were crystallized by an excimer laser. Electron carrier mobilities of 80-100 cm2/V.sec were achieved in the poly-Si films obtained.

At the time of the WTEC team's visit, the most significant work underway with implications for advanced display was the patterned growth of silicon needles. The growth technique, called the vapor-liquid-solid technique, allowed the growth of very sharp needles that are potentially useful for preparation of field emission tips. The growth must be performed at 900-1000 degrees centigrade. The needles could be formed in regular arrays over an area of 1 cm2 by applying a pattern of Au dots using standard photolithography. The needles form where the Au is deposited. Some tips, prepared from the needles, were only a few tens of at their ends. The researchers were attempting to detect quantum size effects. A second area of interest was to generate photoluminescence or electroluminescence from large areas covered by tips. Needle growth had also been demonstrated with InAs and GaAs.

The laboratory under Dr. Givargizov has succeeded in growing diamond particles (polycrystalline or single-crystal) on the tips of the needles from an H2-CH4 gas mixture. The particles shown to the WTEC team were about 0.2 to 2 şm in diameter. The institute's scientists had not yet controlled the deposition process well enough to form a diamond particle on the tip of every needle, nor to prevent nucleation on the sides of the tips. Our hosts expressed the belief that they will be able to dope the diamond particles for negative electron affinity. The testing of the diamond-coated emitters, just beginning at the time of the WTEC visit, has shown encouraging results as reported in the latest correspondence from Dr. Givargizov [Oct. '94]. Additional information on these developments is included in Vacuum Fluorescent, Electroluminescent, Field Emission, and Other Emissive Displays of this report.

SUMMARY

The Institute of Crystallography is involved in basic crystal growth research not tightly coupled to device technology. In the area of patterned silicon needle growth, the institute has made impressive progress. The deposition of diamond microspheres on the silicon needles could have significant applications in field emitter devices, especially if uniformity of deposition can be achieved and if the diamond spheres can be doped for negative electron affinity.


Published: December 1994; WTEC Hyper-Librarian