Electrical spin injection into the InAs/GaAs wetting layer

We have used transport measurements, transmission electron microscopy, and polarization dependent photo- and electroluminescence to characterize the InAs/GaAs(001) wetting layer (WL) system. Transport data confirm formation of a two-dimensional electron gas in modulation-doped structures. The optical pumping of the WL in an undoped structure provides a ratio of radiative to spin lifetime (tau(r)/tau(s))similar to 1, which is constant over the measurement range of 10-100 K. We demonstrate efficient spin injection from an Fe Schottky tunnel contact into the WL, and achieve an electron spin polarization of similar to 55% from 5 to 50 K, which decreases monotonically with increasing temperature. (c) 2007 American Institute of Physics.