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Special Seminar

Manufacturability at the Nanoscale

by: Dr. Christie Marrian

Date: Thursday April 07, 2005

Time: 12:00 pm – 1:00 pm

Location: Houston Science Center – Building 593 — Room 102

Overview

Using the 2005 IBM Global Technology Outlook, I will describe the roadmap for device technology and manufacturing in the semiconductor industry. Looking beyond these roadmaps, I will discuss moving beyond our current methods of fabrication of nanoscale devices and circuits. These almost always rely on heroic efforts of nanofabrication that are inappropriate for anything other than research. To achieve, at the nanoscale, any level of volume manufacturing requires more than extensions of the paradigms practiced today. We must look to Nanotechnology for help in overcoming this challenge as to fail to do so will consign nanostructure science and technology to be a mere intellectual curiosity.

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Special Seminar

Recent Issues in Data Storage

by: Prof. Erik Svedberg

Date: Thursday April 07, 2005

Time: 10:00 am – 11:00 am

Location: Houston Science Center – Building 593 — Room 102

Overview

The “trilemma” of data-storage is becoming more challenging as the packing density of information continues to increase on disc drives. We are today aiming to reach a density of 1Tbit/in2. The conflicting magnetic requirements while shrinking the bit size will be described in this presentation and I will visit some of the interesting challenges in materials science and measurement technology encountered during my last five years working in this area. The presentation will touch upon AFM/MFM measurements used for determination of signal-to-noise ratios and data aging. There is always a need to “see” what you have recorded, not only to receive a feedback signal from the system under study. Nano-particles versus grains in thin films and statistical size analysis will be included as it is an important aspect for future technologies. Today grain size distributions rely largely on SEM and TEM images that provide too little statistical material. Electroplated nano-junctions present the possibility of novel properties that are e.g. useful in sensors for reading stored information. As the bit size shrinks the magnetic signal is reduced and there is a search for more sensitive detectors. Combinatorial approaches to material science and x-ray diffraction (XRD) texture determination of important magnetic materials, such as FePt, will also be discussed. The complex factors determining the magnetic thin film properties can be initially screened and optimized in ways similar to advanced drug discovery.

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Special Seminar

Thin Film Hetero Structure Solid Oxide Fuel Cell

Prof. Alex  Ignatiev

by: Prof. Alex Ignatiev

Date: Thursday March 24, 2005

Time: 12:00 pm – 1:00 pm

Location: Houston Science Center – Building 593 — Room 102

Overview

A thin film solid oxide fuel cell (TFSOFC) with significantly reduced operating temperature has been developed based on thin film deposition and photolithographic processing. The unique thin film SOFC design incorporates a thin film (<1 micron) oxide electrolyte, deposited on a nickel foil substrate by pulsed laser deposition and MOCVD, and deposition of a micro porous thin film conducting oxide La0.5Sr0.5COO3 (LSCO) cathode on top of the electrolyte thin film forming the fuel cell heterostructure. The nickel substrate is then made porous (and thus becomes the cell anode) by photolithographic patterning and etching. This thin film SOFC structure results in operating temperatures as low as 450°C, which now allows for the utilization of more standard cell support materials and also results in much reduced thermal stress and thermal degradation. The thin film SOFC has stably operated in a temperature range of 450-570°C, significantly lower than bulk SOFC's, and has yielded a maximum output power density of ~110mW/cm2 in that temperature range. The low operating temperatures coupled with the nickel anode also allow for the direct conversion of hydrocarbons, especially methane and methanol without the problem of coking, thus resulting in a true self-reforming SOFC. The thin film character of the thin film SOFC when integrated with thin film interconnects is expected to result in a high power to volume ratio (= 10 W/cm3), which will be important in a variety of power applications.

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Special Seminar

Computational Materials for CMOS Technology

by: Prof. Alex Demkov

Date: Thursday February 03, 2005

Time: 4:00 pm – 5:00 pm

Location: Houston Science Center – Building 593 — Room 102

Overview

In order to continuously improve the transistor performance the semiconductor industry is exploring a variety of novel structures and materials that only recently were considered only in long-range R&D labs. Such systems include SOI, strained Si on SiGe, and high-k dielectrics for the gate along with pure metal gates instead of poly-Si, low-k dielectrics for ILD etc. Along with these revolutionary technologies, industry pays close attention to squeezing every bit of performance from the existing platforms, strain engineering and effects of shallow trenches is one example. Traditional TCAD tools often lack physical models capable of describing all these new systems, and atomic level modeling is being considered as an important tool in the mainstream semiconductor development. Thus the intrusion of “exotic materials” and significant developments of the atomic scale modeling over the past decade made it possible to derive value from a fairly academic discipline. In this talk I will show how the CMOS roadmap brings about a strange marriage of quantum mechanics and transistor manufacturing.

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Special Seminar

Bi2Sr2CaCu2O8+δ c-Axis Twist Josephson Junctions: The Superior Test of Order Parameter Symmetry

by: Prof. Richard A. Klem

Date: Tuesday December 07, 2004

Time: 4:00 pm – 5:00 pm

Location: Houston Science Center – Building 593 — Room 102

Overview

Three c-axis twist Josephson junction experiments to test the symmetry of the superconducting order parameter have been performed on Bi2Sr2CaCu2O8+d. These are the experiments performed on bicrystals [Q. Li et al., Phys. Rev. Lett. 83, 4160 (1999)], on artificially prepared cross whiskers [Y. Takano et al., Phys. Rev. B 65, 140513 (2002); Physica C 408-410, 296 (2004)], and on naturally-formed cross whiskers [Yu. I. Latyshev et al., Phys. Rev. B 70, 094517 (2004)]. These experiments are analyzed in terms of the twist theorem for weak, first-order c-axis tunneling between two d-wave superconductors twisted 45- about the c axis, with treatments of weak, first-order c-axis tunneling matrix elements with varying amounts of coherent and incoherent components and order parameter forms, including the effects of the Fermi surface details, strong coherent tunneling, orthorhombicity, nanoscale disorder, and order parameter twisting near the physical twist junction. It is shown that in all three experiments, essentially all of the c-axis Josephson tunneling arises from an s-wave component to the superconducting order parameter, and that the overall order parameter must contain a substantial s-wave component for T & TC. In addition, the c-axis tunneling in the bicrystal and natural cross-whisker experiments must be strongly incoherent. New calculations for in-plane (001) tilt grain boundary junctions relevant to the IBM tricrystal and related phase-sensitive experiments will also be presented.

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