| Popis: |
A comprehensive study on lateral-type spin-photodiodes based on metal-insulator-semiconductor junctions operating at room temperature is presented. The performance of a simple cleaved-edge Fe/AlOx/p-GaAs Schottky junction spin-photodiode has been investigated. In addition to conventional sidewall illumination experiments, oblique angle surface illumination measurements were also carried out. Experimental results show a spin collection efficiency F of 0.14% for sidewall illumination, and an improved F of 1.3% for oblique angle surface illumination. A simulation model based on the optical selection rules, carrier and spin drift-diffusion, and spin dependent tunneling has also been developed. Simulation results show a good match with experiment data for oblique angle illumination. A further comparison of experiment and simulation results suggests that the low F for side illumination has been caused either by the damage to the AlOx tunnel barrier at the cleaved edge or by magnetic edge curling. Furthermore, a novel Fe/AlOx/p-InGaAs spin-photodiode design with a refracting facet has also been presented. An experimental F of 0.4% has been achieved for the fabricated refracting-facet spin-photodiodes. This value is the highest so far for purely lateral spin-photodiodes. In addition to experiments, a simulation model for the refracting-fact spin-photodiode involving the optical selection rules, carrier and spin collection probability, and spin-dependent tunneling, has also been developed. Simulation results show that a potential F up to 19% is achievable for the proposed spin-photodiode design. A comparison of the simulation and experimental results suggests that the quality of the Fe electrode is poor, and that an improvement of the electrode quality will lead to a significantly enhancement in the F. With these results, a significantly improved understanding of the physics of lateral spin-photodiodes, as well as a practical demonstration of a lateral spin-photodiode, has been achieved. |
