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 8nm and 60nm and length between 100nm and 1000nm. 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. Nano-ferroelectric domains were found in Rochelle salt crystals grown inside the alumina nano-pores [1-2]. Pyroelectric detection of infra-red radiation at wavelengths of 8-12microns were recorded from Tri-Glycine Sulfate crystals grown inside the alumina nano-pores. Piezoelectric response was measured by potassium Iodate crystals grown inside the alumina nano-pores having a high figure-of-merit . This highly dense array of non-linear dielectric crystals is aimed for highly sensitive detectors and sensors of light and mechanical pressure.
D. Yadlovker and S. Berger, “Uniform orientation and size of ferroelectric domains” Phys. Rev. B, 71, 184112 (2005).
D. Yadlovker and S. Berger , ” Nucleation and Growth of Single Crystals with Uniform Crystallographic Orientation Inside Alumina Nano-pores”, J. Appl. Phys., 101, 034304 (2007).
M. Nitzani and S. Berge, “Pyroelectric nano-rods grown inside alumina nano pores”, Physica E, 37, 260-264 (2007).
R. Yasinov M. Nitzani, and S. Berger, ” Ferroelectric properties of KIO3 nanorods grown inside aluminum oxide pores”, Ferroelectrics, 390, 153-159 (2009).