Separation of spin and charge currents by photovoltage measurements in n-InGaAs

Spin photocurrents have gained strong attention in the field of spintronics as they convert spin information into electric voltage and spin-polarized currents. Many effects yielding spin-photocurrents have been demonstrated in 2DEGs, e.g. spin-galvanic effect and magneto-gyrotropic photogalvanic effect. However, no direct proof of the spin polarization of these currents has been reported yet. We present photovoltage measurements on n-InGaAs epilayers combined with Faraday rotation spectroscopy for the detection of the spin polarization. The photovoltage consists of both a light polarization dependent and an independent component which exhibit different energy dependencies. Comparison with the spin sensitive measurements of the Faraday rotation allows us to separate spin from charge voltages.