Spin injection across ( 110 ) interfaces: Fe ∕ GaAs ( 110 ) spin-light-emitting diodes

We report electrical spin injection from an Fe contact into a ( 110 ) -oriented light-emitting diode (LED) structure, and compare results with data obtained from ( 001 ) -oriented structures to address the dependence of spin injection on interface and orientation. Fe ∕ AlGaAs ∕ GaAs LEDs were grown by molecular-beam epitaxy, and processed to form surface emitting structures. Electroluminescence results obtained using a reverse-biased Fe Schottky tunnel barrier injector show that a 13% electron spin polarization is achieved in the GaAs ( 110 ) quantum well due to injection across the Fe ∕ AlGaAs ( 110 ) interface. Analysis of the transport data indicates that tunneling is a significant transport mechanism at low temperatures. The temperature dependence of the spin polarization is similar to that of (001)-oriented spin LEDs, and is dominated by the GaAs electron spin lifetime.