Spin injection from CoFe/MgO tunnel injectors into GaAs

The primary goal of research in spin injection has been to create a population of highly spin-polarized carriers inside a semiconductor at room temperature for potential manipulation in a spin-based device. Using quantum well electroluminescence detection, the CoFe/MgO tunnel spin injector has demonstrated greater than 50 {\%} polarization of electrons inside GaAs at 100 K as well as polarizations exceeding 30 {\%} at 290 K. In addition, the structures are thermally stable, showing no decrease in injected polarization even after exposure to temperatures as high as 400 $^{o}$C. Both spin relaxation rate and recombination lifetime play a role in determining the measured polarization. The temperature and bias dependence of the polarization between 1.4 K - 290 K will be discussed.