Enhanced Magneto-Optical Kerr Effect of GaAs-Based P-N Junctions in the Terahertz Range

We demonstrate that the magneto-optical Kerr effect at normal incidence in the terahertz (THz) frequency range is useful for evaluating carrier transport properties of particular layers of a p-n junction. Since a single p-type thin film only exhibits a small magneto-optical Kerr effect, magneto-optical Kerr spectroscopy cannot be used to determine the carrier densities of such a film with high sensitivity. However, because the electric field is enhanced at the p-layer in a p-n junction due to the interference between the THz waves that are reflected at the highly doped substrate and the p-layer at the surface, it is possible to conduct magneto-optical Kerr spectroscopy with a higher sensitivity. We numerically calculate and experimentally determine the spectra of the ellipticity and polarization rotation angles for single n- and p-GaAs epitaxial layers and GaAs-based photovoltaic devices with a p-i-n structure and evaluate the carrier densities of the n- and p-layers. At normal incidence, this method has a high spatial resolution, which is beneficial for imaging of large-area devices.

Automated summary

The magneto-optical Kerr effect at normal incidence in the terahertz frequency range is useful for evaluating carrier transport properties in specific layers of a p-n junction. Enhanced electric field at the p-layer in a p-n junction allows for higher sensitivity magneto-optical Kerr spectroscopy. Numerical calculations and experimental measurements can be used to determine carrier densities of n- and p-layers in GaAs epitaxial layers and devices with a p-i-n structure. This method offers high spatial resolution for imaging large-area devices.