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Lecture Ashish Arora


13 August 2012 FWN-Building 5115.0017, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. Ashish Arora
Affiliation: Tata Institute of Fundamental Research, Mumbai, India
Title: Polarization resolved optical and magneto-optical studies on III-V semi-conductor bulk and quantum well structures
Date: Mon Aug 13, 2012
Start: 11.00
Location: FWN-Building 5115.0017
Host: C.H. van der Wal
Telephone: +31 50 363 4974


Polarization resolved spectroscopic measurements on semiconductors and
their nanostructures provide useful information regarding their electronic
band structure (EBS). We discuss two examples, one where a sample is under strain and another where it is under an external magnetic field. In the first example, linear polarization resolved lateral-photoconductivity measurements on specially fabricated GaAs/AlGaAs quantum well (QW) device structures demonstrate that anisotropic strain present in the plane of the QW leads to valence band mixing which modifies the transition selection rules, giving rise to in-plane polarization anisotropy. Thereafter we discuss the case of GaAs/AlGaAs QWs and bulk GaN under magnetic fields whose influence on the EBS is to introduce Landau levels and Zeeman splitting. We show that a sensitive way of probing the spin-split EBS is through magneto-optical Kerr effect (MOKE) spectroscopy performed using circular polarization modulation with a photoelastic modulator. This technique enables determination of very small excitonic Zeeman splittings and helps determine Lande g-factors in QWs under low magnetic fields (< 1.8T). A well width dependent study of electron-heavy hole and electron-light hole exciton g-factors is presented and compared with*k.p* theory based calculations. Finally MOKE spectroscopy results on polar and non-polar bulk GaN will be presented.

Last modified:22 October 2012 2.30 p.m.