Electric-field induced modification of the photoluminescence polarization in Ge/Si0.15Ge0.85 quantum wells

Abstract

The manipulation of the spin degree of freedom is highly sought after in the field of spintronics. This study looks at the emergence of Rashba physics in group IV materials, such as p-i-n diodes that contain Ge quantum wells and Si 0.15 Ge 0.85 barriers. By using optical spin orientation, it was found that the circular polarization degree of the direct emission can be increased by increasing the power of the optical pump, while the device remains unbiased. This is attributed to the optical-induced changes in the built-in Rashba field due to the asymmetric doping of the diode structure. These findings can provide a new way to fine-tune the material properties for spin quantum electronic and optical applications.