- B.Sc. 1983 (Technion)
- D.Sc. 1990 (Technion)
After receiving his doctorate, Assoc. Prof. Berger spent two years as a research associate in the Department of Materials Science & Engineering at the Technion, and one year as a Rothchild research fellow in the Division of Applied Science at Harvard University. In addition, he carried out research at Battelle Frankfurt for three months. In 1993 he joined the Department of Materials Sience & Engineering at the Technion.
The main interest of our group is dielectric nano-composite thin films. The films consist of a highly dense array (1010-11/cm2) of crystals grown inside alumina pores. The pores have an average diameter between 20nm and 60nm and length between 100nm and 50mm. The pores are prepared by electrochemical anodization of pure aluminum films and oriented in-vertical to the film plane. Non-linear dielectric crystals were grown inside the alumina nano-pores with preferred crystallographic orientation along the longitudinal axis of the pores. In some cases the preferred crystallographic orientation is the polar axis. The preparation of the alumina porous film and growth of the crystals inside the nano-pores is carried out in our laboratory.
The major research work is focused on studying and correlating the microstructure, chemical composition and dielectric properties of the crystals inside the alumina nano-pores. Our recent study reported a detection of low mechanical pressures, as low as 1Pa, by piezoelectric nano-crystals.
A. Ostrovsky and S. Berger
“Boracite Nano-Crystals Formation Inside Alumina Nano-Pores at Low Temperatures from Aqueous Solution”.
Advanced porous Materials, vol.5, 1-6 (2017).
H. Beshara and S.Berger
“Piezoelectric ultra-sensitive aluminum nitride thin film of flexible aluminum substrate” Journal of Material Science, 53:1246-1255 (2018).
H. Beshara and S. Berger
“Highly sensitive piezoelectric response of Sodium Nitrite nano-crystals to low applied mechanical pressures”. Journal of Material Science and Engineering A 8(5-6), 85-94 (2018).
Chapters in Books
“Dielectric Properties of Nanoparticles”, Review chapter (#13) in a Book Series on Advances in Nanophase Materials and Nanotechnology, ( Functionalization and Surface Treatment of Nanoparticles), Vol. Editor Marie Isabelle Baraton, Managing Editor, H.S. Nalwa, American Scientific Publishers, CA, USA, August, 2002.
“Dielectric Properties of Nanoparticles” Review chapter in the Encyclopedia of Nanoscience and NanotechnologyT ” Edited by H.S. Nalwa, American Scientific Publishers, CA, USA, March 2004.
Currently, the research activities of our group are focused on dielectric nano-crystals and thin films. We study the dielectric behavior of nano-crystals as a function of their microstructure, composition and size. In our lab we grow nanometer-size dielectric crystals inside a highly-dense array of alumina nano-pores. The crystals are grown from over-saturated liquid solutions with preferred crystallographic orientations under a tight control of temperature and composition. The crystals nucleate at the bottom of the pores and grow along the longitudinal axis of the pores. The surface morphology and microstructure of the crystals are characterized using HRSEM. The crystallographic phase and orientation of the crystals are determined using XRD analysis. The composition and nature of chemical bonds are identified by AES, SIMS and FTIR. The dielectric properties are measured using LCR impedance analyzer and Radient instruments. The pyroelectric response is measured in a specially designed set-up where the temperature of the crystals is time- modulated and the pyroelectric current response is measured. The piezoelectric response of the crystals is measured by exposing the crystals to time-modulated mechanical force and measuring the piezoelectric current response.