The influence of the Fe Ga0.9 Al0.1 As interface on spin injection into a spin light-emitting diode is studied. Spin injection is found to depend strongly on the interfacial doping profile demonstrating the importance of band bending in the semiconductor near the interface. The effect of post-growth annealing on spin injection from Fe contacts into GaAs-based spin light-emitting diodes is also examined. Post-growth annealing up to 250 °C is found to increase the spin injection efficiency. It is demonstrated that the annealing modifies electronic properties of the Fe Ga0.9 Al0.1 As interface, as evidenced by an increase of the Schottky barrier height.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures|
|State||Published - 2005|
Bibliographical noteFunding Information:
The authors thank the Minnesota Nanofabrication Center for providing the facilities for device processing and acknowledge financial support by the DARPA SPINS Program, ONR, and the University of Minnesota MRSEC (NSF DMR-0212032). FIG. 1. (a) Schematic of the spin LED structure; (b) optical micrograph of a processed LED device. FIG. 2. (a) Magnetic field dependence of the electroluminescence polarization P EL from spin LEDs with different interfacial n + doping levels, as indicated ( T = 20 K ) . The bias conditions are 14.1, 22.6, and 35.4 A cm − 2 for the samples with 3, 5, and 6 × 10 18 cm − 3 interfacial doping, respectively; (b) bias dependence of the electroluminescence at B = 25 kOe for spin LEDs with different interfacial n + doping levels, as indicated ( T = 20 K ) . FIG. 3. Maximum electroluminescence polarization P EL as a function of interfacial n + doping level for as-grown samples and after annealing at 250 °C for 1 h. The dotted line indicates the typical background signal due to magnetoabsorption in the Fe layer. FIG. 4. (a) Current–voltage characteristics of an Fe – Ga 0.9 Al 0.1 As Schottky contact ( n = 5 × 10 18 cm − 3 ) as-grown (solid line) and after annealing at 250 °C (dashed line); (b),(c) differential conductance spectra of the same sample. All measurements T = 10 K . FIG. 5. (a) Magnetic field dependence of the electroluminescence polarization P EL from spin LEDs after post growth annealing at different temperatures, as indicated ( T = 20 K ) ; (b) bias dependence of the electroluminescence at B = 25 kOe for spin LEDs after post growth annealing at different temperatures, as indicated ( T = 20 K ) .