The influence of tunnel effect on the current injection of spin light-emitting diodes with InGaAs/GaAs quantum wells

By using current-voltage characteristic and electro-photo luminescence measurements, the efficiency of spin electronic injection was investigated in the Co/Al_2 O_3 tunnel barrier/GaAs based structure, where spin current was generated by electric injection from FM to GaAs through the tunnel barrier. The investigations were performed on the devices with different tunnel barrier thickness of Al_2 O_3 surmounted by a thin Co ferromagnetic layer. The increase of the effectiveness of the electrical injection was identified by an increase in the intensity of electroluminescence; thereby we can define the optimal thickness of the layer of Al_2 O_3 as a tunnel and as a diffusion barrier. Also, manipulation of the tunneling barrier thickness leads to control of emission threshold of diode structures and sensitive diode. We also demonstrated the dependence between the tunneling barrier thickness and Schottky barrier height and the resistance of diode structure.