Prof. Goldfarb Ilan Associate Professor School of Mechanical Engineering The Iby and Aladar Fleischman Faculty of Engineering Tel Aviv University 69978 Ramat Aviv, ISRAEL                       +972-3/6407079 (office)                       +972-3/6405931 (lab)                      +972-3/6407617 (fax) ilang@eng.tau.ac.il

---

Research Interests:

Research Interests:

My research interests are in the field of surface science, in general, nanostructures in particular, and related phenomena, such as adsorption, desorption, diffusion, segregation, nucleation and growth, phase transitions, self-assembly and self-organization, etc.  These surface processes play a key role in epitaxial and heteroepitaxial film growth, heterogeneous catalysis, and MEMS technology.  For example, I have been exploring the links between strain relaxation processes and surface/interface energies, and the morphological evolution of surfaces growing under strain, e.g., self-assembly of nanodots in heteroepitaxy. This fascinating phenomenon is not only interesting from the fundamentally physical standpoint, but bears important implications for semiconductor and other hi-tech industries. To investigate such correlations I have been using real-time scanning tunneling microscopy (STM) monitoring of nucleation and growth of nanostructures, that appear on the strained surfaces during growth. A combination of real-time atomic-resolution STM with high (RHEED) and low) LEED) energy electron diffraction, is a very powerful method of probing the surface morphology and crystallography.
        For example, Ge/Si(001)  is a classical example of a Stranski-Krastanow growth, where the initial two-dimensional wetting layer grows pseudomorphically, i.e.strained due to the 4.2% Ge/Si lattice mismatch.

        Fig. 1 

Fig. 1: These Ge/Si(001) islands, otherwise known as "hut clusters" because of their hutlike shapes formed by {501} facets inclined at 11 degrees to the (001) bases, owing to their small dimensions and crystalline perfection can exhibit the electron confinement properties of quantum dots.

CoSi2/Si(001) grows in a Volmer-Weber mode with a -1.2% mismatch, and is an example of a layer under relatively small tension. In spite of these differences, the early stage growth results in a very similar appearance of nanodots in both cases. On the other hand, analysis of the late growth stages indicates different growth mechanisms. Understanding the mechanisms underlying these similarities and differences will allow to intentionally "engineer" the desired surface morphologies and properties.

        Fig.2

Fig. 2: Typical atomic-resolution STM image of (221)-oriented CoSi2 nanocrystals, grown on Si(001) by reactive deposition epitaxy.
The image size is 35 nm X 35 nm.

Fig. 3 & 4: CoSi2 nanostructures at various stages of evolution (dots and wires)

"Semiconducting iron-silicide can be two-dimensionally grown on
Si(111), as an ordered hexagonal network".

  "Complex interactions cause titanium-silicide nanocrystals to develop
fascinating facets and shapes, when growing on Si(111)"

"For device applications, it is important not only to self-assemble the nanostructures, but to order them into defined geometrical patterns, as well. Vicinal (miscut) surfaces consist of periodic terrace-step arrangements, which can be used as natural templates for such ordering. In the figure below, self-organization of self-assembled CoSi2 nanocrystals on the step-trains of vicinal Si(111) surface is shown"

My new laboratory at Tel Aviv University expands the research options even further.  It is centered around state-of-the-art multifunctional ultra-high vacuum (UHV) Microlab, who’s heart is a variable-temperature (25-1500K) scanning probe microscope (SPM), including both scanning tunneling (STM) and beam-deflection atomic force (AFM) microscopy options, capable of time-resolved monitoring of epitaxial growth from a computer-controlled, precise three-pocket e-beam evaporator.  In addition the microlab includes RHEED, LEED/AES, mass-spectrometer, sputter-ion gun, and other useful tools and techniques of surface
science.

My research group:

Yevgeni Roizinev (M.Sc), Lilach Bezalel (M.Sc), Shirley Carmi (M.Sc), Tzur Genosar (M.Sc., with L. Banks-Sills), Gili Cohen-Taguri (Ph.D), Oren Levy (Ph.D., with M. Nathan), Mario Levinstein (Technical Support).
Graduated: Gili Cohen-Taguri (M.Sc), Steve Grossman (M.Sc).

Publications

Return to:

[ Solid Mechanics | Engineering | Tel Aviv University ]

Please send comments or questions about this page to ilang@eng.tau.ac.il
Last modified: Mon Mar 25  2002