Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 4: II-VI semiconductors
HL 4.3: Vortrag
Montag, 23. März 2009, 10:45–11:00, POT 51
High temperature magnetic polaron formation in Mn-doped CdSe nanoparticles — Lars Schneider1, •Gerd Bacher1, Rémi Beaulac2, Paul Archer2, and Daniel R. Gamelin2 — 1Werkstoffe der Elektrotechnik und CeNIDE, Universität Duisburg-Essen, 47057 Duisburg — 2Department of Chemistry, University of Washington Seattle, WA 98195-1700 (USA)
Transition metal doped semiconductor nanoparticles have attracted great interest because of their high application potential in spintronics and optoelectronics. E.g., doping with Manganese (Mn) can create interesting magnetooptical effects in CdSe nanoparticles [1]. Here we present time resolved photoluminescence (PL) measurements on size selected Mn-doped CdSe nanoparticles from the liquid phase. Nanoparticles with a mean particle diameter of 5nm and a Mn-content of 4.2% show at T = 5K a huge transient red shift of about 140 meV in contrast to less than 30 meV observed in CdSe reference nanoparticles of similar size. We attribute this to the formation of an exciton magnetic polaron (EMP)with a large internal exchange field. From the transient energy shift we are able to extract a characteristic time constant of 150 ps, which fits quite well to the magnetic polaron formation in self organized CdSe/ZnMnSe quantum dots [2]. Although the transient energy shift gets weaker with increasing temperature, a clear indication of magnetic polaron formation even above 200K is observed demonstrating the highest temperature ever obtained for EMP formation. [1]Beaulac et al., Nanoletters, 8 (2008), 1197. [2]Seufert et al., Phys. Ref. Lett., 88 (2002) 027402