Exploring of Bulk and Structure Inversion Asymmetry in GaAs/AlGaAs Quantum Well Structures Applying Spin Photogalvanics

The project is aimed to the investigation of bulk (BIA) and structure (SIA) inversion asymmetry in semiconductor quantum well (QW) structures. Inversion asymmetry in QW structures and its manipulation play an important role for the generation, manipulation and detection of spin polarized electrons in semiconductor systems. To gain the information on BIA and SIA we will use a novel technique developed by our group in the framework of the first part of the project. The technique is based on investigation of terahertz radiation induced photogalvanic effects, comprising magneto-photogalvanic effect, circular photogalvanic effect and spin-galvanic effect. The project is focused on investigation of BIA and SIA in various Ill-V-compound materials of different crystallographic orientations. In particular, the behavior of the inversion asymmetry upon variation of temperature, QW shape and carrier density will be studied, Our preliminary results obtained on (llO)-oriented structures demonstrated that the structure inversion asymmetry can be controllably tuned to zero by variation of (-doping layer positions. This method should be extended to (00l)-grown structures providing an information on growth conditions needed to obtain perfectly symmetric structures with zero Rashba constant and structures with equal Rashba and Dresselhaus spin splittings. The latter structures should show extremely long spin relaxation times and are of particular interest for realization of spin transport based devices.