Optical spin polarization measurements on indium arsenide-based light emitting diodes
Stier, Andreas Volker
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The general approach for examining the large variety of spin-related phenomena in metals and semiconductors is to introduce or otherwise prepare a collection of aligned spins and study the response of that system to external conditions like an asymmetric potential, or an applied electric or magnetic field. This work focuses on measuring the injection of spins into the narrow gap semiconductor Indium Arsenide (InAs) from a CdMnSe spin-aligner by the optical polarization degree of the radiation emitted from a light emitting diode structure with InAs as the active layer material. In order to improve the signal-to-noise ratio of the very weak electro-luminescence (EL) from these diodes, a single layer anti-reflection coating (ARC) of silicon monoxide (SiO) was developed, and applied on the samples. A positive optical circular polarization degree was found in the polarization measurements on recent samples grown at the University of Würzburg, suggestive of significant spin injection from the CdMnSe spin-aligner. These results indicate that we have successfully injected spins into InAs for the first time.