Optical and Magneto-Optical Properties of Emerging III-V Bismides

Data: 
11/11/2014 - 13:30 até 14:30
Palestrante: 
Profa. Dra. Yara Galvão Gobato
Local: 
Sala de Reuniões do Edifício Mário Schenberg, DFMT
Resumo: 

Dilute III-V bismide materials have attracted much attention in the last years due to their unusual fundamental physical properties such as a large band gap reduction (about 85meV per percent of Bi) and a strong enhancement of the spin orbit splitting due to incorporation of Bi in GaAs . These remarkable properties make them promising materials for several applications in spintronics and for long-wavelength optoelectronics such as high efficient and temperature stable semiconductor lasers. However, from the technological point of view, the quality of such material is still in the stage of the optimization of their growth conditions in order to obtain high quality properties required for technological applications. In this presentation, we  review optical, magneto-optical and structural studies of GaBixAs1-x layers and nanostructures grown by Molecular Beam Epitaxy (MBE) on (311)B and (001) GaAs substrates. It was observed that under near-stoichiometric conditions the bismuth incorporation is higher for samples grown on (311)B GaAs substrates than for those grown on (001) GaAs. In addition, carrier localization effects in GaBiAs layers are clearly revealed for both samples by optical measurements. It has also been found that the nonradiative centers play a significant role in the recombination process in this material system. The influence of post-growth annealing on the microstructural, optical, and magneto-optical properties have been also investigated. An important improvement of optical and spin properties after thermal annealing due to the reduction of defects in the GaBiAs layers was observed.