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Lecture D. Turchinovich

Rooster

WanneerWaar
11 april 2006 FWN-Building 5113.0201, Nijenborgh 4, 9747 AG, Groningen
Speaker:Dr. D. Turchinovich
Affiliation:Atom Optics and Ultrafast Dynamics, Debye Institute, University of Utrecht
Title:Time-resolved THz experiments on semiconductor nanostructures
Date:Tue Apr 11, 2006
Start:15.00
Location:FWN-Building 5113.0201
Host:P.H.M. van Loosdrecht
Telephone:+31 50 363 8149 / 4974

Abstract

In this presentation we will discuss the basic physics behind THz generation and detection using femtosecond laser pulses, as well as the novel experiments performed on the semiconductor nanostructures. Ultrafast polarization dynamics in an optically pumped internally biased piezoelectric InGaN/GaN quantum well (QW) structure will be studied using THz emission spectroscopy. It will be shown that the bias electric field on the order of MV/cm in such a QW can be completely screened by the optically excited carriers on a time scale shorter than the laser pump pulse duration. Such an optically induced screening is a very nonlinear process and strongly influences both optical and electronic properties of the sample. We will also discuss the ultrafast carrier dynamics in Stranski-Krastanow grown InAs/GaAs quantum dot (QD) structure studied in an optical-pump THz-probe experiment. It will be shown that the presence of QDs significantly reduces the free-carrier lifetime due to efficient trapping process, still keeping the carrier mobility high, thus making such structures potentially promising for ultrafast optoelectronics.
Laatst gewijzigd:22 oktober 2012 14:30