화학공학소재연구정보센터
Applied Surface Science, Vol.473, 230-234, 2019
Interfacial influence on electrical injection and transport characterization of CoFeB vertical bar MgO vertical bar GaAs-InGaAs quantum wells hetero-structure
The quality of interfaces is a key factor for efficient electrical spin injection into quantum well light emitting diodes. Here, we investigate the interfacial influence on the electrical transport properties in CoFeB vertical bar MgO vertical bar GaAs-InGaAs quantum wells hetero-structure, by considering textured MgO tunnel barrier fabricated by two different techniques: sputtering and molecular beam epitaxy (MBE). From forward and reverse current-voltage characteristics, it is found that the threshold voltage decreases as the annealing temperature changes from room temperature to 300 degrees C for sputtered samples, however there is not much difference in threshold voltage with the annealing temperature for MBE-grown samples. In combination with transmission electron microscope (TEM) studies, it is found the MgO vertical bar GaAs interface by MBE is sharp for both grown and annealed states. However, there is a thin (similar to 0.4 nm) amorphous MgO layer at the MgO vertical bar GaAs interface for sputtered samples with grown state, and the amorphous MgO can be improved and crystallized after annealing. The MgO vertical bar GaAs interface plays a role in modulating the band structure and has an influence on electrical injection. Our work demonstrated that CoFeB vertical bar MgO vertical bar GaAs interfaces are important and can be engineered thanks to the use of two types of growth for the textured MgO tunnel barriers, which ensures efficient electrical injection.