Engineering Commons^™

Rough Interfaces In Thz Quantum Cascade Lasers, Tillmann Kubis, Gerhard Klimeck

Gerhard Klimeck

The impact of interface roughness scattering on the device performance of state-of-the-art THz quantum cascade lasers is theoretically analyzed using the non-equilibrium Green’s function formalism. It is shown that for a particular direct transition QCL design style rough interfaces hardly change the electronic energy spectrum, but dramatically reduce the occupation inversion and the optical gain. A spatial separation leading to a diagonal transition laser, leads in contrast to a limited sensitivity to interface roughness. Diagonal transition QCL designs result in a better device performance and an improved reliability with respect to interface roughness induced by growth quality variations.

A Comprehensive Atomistic Analysis Of Bandstructure Velocities In Si Nanowires, Neophytos Neophytou, Hans Kosina, Gerhard Klimeck

Gerhard Klimeck

A 20 band sp3d5s* spin-orbit-coupled, semi-empirical, atomistic tight-binding (TB) model is used with a semi-classical, ballistic transport model, to theoretically examine the bandstructure carrier velocity under non-degenerate conditions in silicon nanowire (NW) transistors. Infinitely long, uniform, cylindrical and rectangular NWs, of cross sectional diameters/sides ranging from 3nm to 12nm are considered. For a comprehensive analysis, n-type and p-type NWs in [100], [110] and [111] transport orientations are examined. The carrier velocities of p-type [110] and [111] NWs increase by a factor of ~2X as the NWs’ diameter scales from D=12nm down to D=3nm. The velocity of n-type [110] NWs also …

Natural Disasters And Early Warning Systems In Australia, Emma Papaemanuel, Katina Michael, Peter Johnston

Professor Katina Michael

Australia's national emergency warning system alerts. Radio program in Greek.

Are Disaster Early Warnings Effective?, Kerri Worthington, Katina Michael, Peter Johnson, Paul Barnes

Professor Katina Michael

Australia's summer is traditionally a time of heightened preparation for natural disasters, with cyclones and floods menacing the north and bushfires a constant threat in the south. And the prospect of more frequent, and more intense, disasters thanks to climate change has brought the need for an effective early warning system to the forefront of policy-making. Technological advances and improved telecommunication systems have raised expectations that warning of disasters will come early enough to keep people safe. But are those expectations too high? Kerri Worthington reports. Increasingly, the world's governments -- and their citizens -- rely on technology-based early warning …

Concern People Without Latest Technology Will Miss Fire Warnings, Sally Sara, Ashley Hall, Peter Johnson, Katina Michael

Professor Katina Michael

But what if the website goes down in the way Victoria's Country Fire Authority website crashed as fires raged a few weeks ago? What about those people who don't own the latest technology? And what happens when the power goes out?

KATINA MICHAEL: Well there's no television, there isn't ability to access the internet potentially.

ASHLEY HALL: Professor Katina Michael is Associate Professor at the School of Information Systems and Technology at the University of Wollongong.

KATINA MICHAEL: I would suggest a long lasting powered radio because we don't want is we don't want when the lights go out, or …