SEMINAR: "Laser Molecular Beam Epitaxy and Multi-functional Thin Films and Superlattices"
July 27 @ 11:00 AM - 12:00 PM - BRK 2001
Professor Zhu Weiguang
School of Electrical and Electronic Engineering
Nanyang Technological University, Singapore
"Laser Molecular Beam Epitaxy and Multi-functional Thin Films and Superlattices"
Tuesday, July 27, 2010, 11:00AM
Birck Nanotechnology Center, Room 2001
ABSTRACT: The Laser Molecular Beam Epitaxy (Laser-MBE) technique is an emerging technology, it has combined advantages of traditional thermal MBE high vacuum and of PLD for high melting materials, and it has become a very promising method to prepare high quality, epitaxial grown thin films for microelectronic and optical devices. The L-MBE can deposit thin films with surface smoothness in atomic scale, especially suitable for high melting temperature ceramics and multi-component solids, such as semiconductors, high-Tc superconductors, optical crystals, electro-optical films, ferroelectric and ferromagnetic materials. It has been very successful and extremely useful for synthesis of artificial-layered super-lattice oxides, ceramics and component materials, to open the possibility of oxide electronics. Recently, multi-functional oxide and ceramic thin films have attracted intensive research interests and attention, and impressive progress has been made in such artificially-designed and grown ultrathin films and super-lattices: for instance, the lager shift of ferroelectric transition temperature in bulk SrTiO3 of ~ 70K up to high than room temperature in ultrathin strained SrTiO3 film; large thermoelectric Seebeck effect in alternative Nb doped SrTiO3 unit cell stacks; co-existence of ferroelectromagnetism; very large 2 dimensional electronic gas and HEMT device, etc.
In this presentation, high-k gate dielectric ultrathin films using Laser MBE will be presented. With continuous scaling down, semiconductor industry, which has annual US$300 billions sales, has approach face tremendous challenges, and one of the focus issues is the using alternative/high-k gate dielectric to replace the currently used SiO2, as rolled out by the International SEMITECH Technology Roadmap for the sub-0.1 μm CMOS technology. 65 nm technology has been in mass production, Intel has used high-k/metal technology for its 45 nm production, and 32 nm and 22 nm technologies, all of which high-k gate dielectrics are employed. Our research work on high-k by L-MBE has generated excellent results, such as equivalent thickness to SiO2 (EOT) of ~ 0.95 nm, extra small leakage current density of ~ 4 orders lower than that of same EOT of SiO2, high breakdown field strength of larger than 10 MV/cm, almost no hysteresis in C-V measurement, and large time-dependent-dielectric-breakdown (TDDB). The breakdown mechanism and conduction mechanism of these high-k gate dielectric ultrathin films will also presented.
The interesting magnetic and electronic properties of ultra-thin films grown by L-MBE have been found to be closely related to the atomically sharp heterointerfaces, like two dimensional electron gas (2DEG) in SrTiO3-LaAlO3 interface and ferromagnetic existing at the interface. More information will be presented during the seminar.
BIO: Dr. Zhu Weiguang received his BSc. and MSc. from Shanghai Jiao Tong University, China, and Ph.D from Purdue University, USA. Currently, He is a Professor at Nanyang Technological University of Singapore, Academician of World Academy of Ceramics, and has been the Immediate-Pass-Chair, Chair, and Chair-Elect of both Asian Ferroelectric Association and Asian
Electroceramics Association. Dr. Zhu is a member of American Ceramic Society, Materials Research Society and a Senior Member of IEEE.
- Keith Bowman