1. STM studies of disordered surface structures:

A Ph.D. project is available in the use of STM to study disordered surface structures. This includes the formation of random surface structures as a result of stochastic kinetic processes. A detailed theoretical analysis on the morphology of these structures will provide much physical insight on such processes. STM will be also used to measure partly disordered (partly amorphous) atomic structures on the surface and the affect of such disordered structures on the local physical characterisitics (such as electronic structure).
Within the framework of this project, questions connected to the interplay between stress and growth in heteroepitaxy (growth of one material on top of another) will be studied.
Working within this project will expose the student to techniques such as UHV-STM, surface preparation techniques (sputter ion gun, electron gun, etc.), surface analysis techniques (LEED, AES, etc.). The work will require also a lot of computer simulations.

This project will be carried out in collaboration with Dr. Zeev Olami, Weizmann Institute of Science, Rehovot.

2. SPM fabrication of submicron- and nano- device structures:

A Ph.D. project is available for using an AFM with a conducting tip for the fabrication of submicron devices. The induction of an electric pulse on surfaces of semioinc materials (materials where ions start to diffuse at high temperatures - examples are Copper Indium DiSelenide, Li doped Silicon, etc.) was found to create devices such as diodes, transistors at the smallest possible sizes (60 nm). The project will involve the fabrication of these devices in different materials with emphasize on reproducibility - the ability to create a uniform size with a certain set of conditions.
After solving the reproducibility problem the next step is the fabrication of these devices on a surface with prexisting mesh to connect them to external electrodes. Then the performance of these devices can be tested. The connection between performance and structure will be studied. The surface structure can be eliminated from the SPM image. It is possible to see with the conducting AFM and the scanning capacitance microscope the different sizes (such as depletion zones) in the transistor, thus it will be possible to follow the operation of the transistor by looking at the images.
Working within this project will expose the student to different types of SPM techniques such as AFM in air, AFM in vacuum and scanning capcitance microscopy. In addition, the candidate will be exposed to problems in nanolithography and in the operation of submicron and nano electronic devices.

This project will be in collaboration with Prof. David Cahen, Weizmann Institue of Science, Rehovot.

2. ESR-STM and nanomagnetism:

A Ph.D. project is available for the development of a new technique in using the STM for observing the dynamics of individual spin centers. Placing an STM tip above a spin center in the presence of an external magnetic field yields an ac component detected at the Larmor frequency. Different spin centers gave different frequencies which enable chemical identification (we could distinguish between Silicon and Iron atoms).
The student will perform experiments on sputtered surfaces. The sputtering creates vacancies on the surface. If these vacancies are paramagnetic, it might be possible to see exchange and dipolar interactions between neighbouringspins. Additional directions of investigation would be to mix the frequency with an external rf signal and detect the difference frequencies in time domain. This will be done with a fast A/D card. This is expected to increase the sensitivity and shed more light on the processes leading to this phenomenon. Additional attempt to detect this phenomenon in liquid helium temperature will be performed. In order to extend the scope of this technique to study molecular spin centers, ESR-STM will be performed also on paramagnetic fullerenes, where fullerenes with encapuslated metal atoms or ions will be studied.
The student will be exposed to UHV-STM techniques, STM performed in air, rf techniques and STM in liquid helium temperatures.

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