The optical Hall effect



Classic electrical Hall effect measurements are standard for electrical characterization of free charge carriers in semiconductor layer structures. We demonstrate that magnetooptic generalized ellipsometry at long wavelengths when applied to conducting or semiconducting multilayer or nanoscopically in-homogeneous structures can yield equivalent and even much increased information. We term this new method optical Hall effect, because it finds simple explanation within the model described by E. H. Hall for the occurrence of the transverse and longitudinal voltages augmented by non-locality of the charge response in time. Transverse and longitudinal birefringence cause magnificent anisotropic polarization responses unraveling rich information on free charge properties of complex-structured samples due to external magnetic fields and collective movement of bound and unbound charge carriers. We demonstrate that with our technique density, type, mobility, effective mass including anisotropy can be measured without any electrical contact in buried structures, and which may have been inaccessible to any true electrical evaluation thus far. We predict a realm of applications for the optical Hall effect in future materials research and engineering. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)