SEMINARI VINCITORI PROCEDURE CONCORSUALI, VALUTATIVE O SELETTIVE
Lunedi 22 luglio alle ore 10.00 in Aula Conversi (Ed. Marconi)
si terrà il seminario sulla sua attività di ricerca, propedeutico ai fini della chiamata, del Dr. Ernesto PLACIDI, vincitore della procedura selettiva RTDB SC 02B1, SSD FIS03 - codice concorso 2018RTDB015.
Increasing the optical efficiency of GaAsBi alloys by strain engineering approach
The development of new semiconductor materials with dilute Bismuth is a topic of great interest among researchers in recent years. GaAsBi alloy exhibits a band gap reduction of up to 90 meV/%Bi, a strong enhancement of spin-orbit splitting (useful to suppress Auger recombination losses) and an almost temperature-insensitive band gap,which are attractive properties for near- to mid-infrared lasers, spintronic devices, photodetectors and terahertz optoelectronic applications.
We applied a growth approach aimed at strain-engineering the pseudomorphic growth of GaAsBi on GaAs(001); such an innovative strategy, never explored in literature, aims to improve the Bi incorporation into the alloy. To this end, we used suitable intermediate InGaAs buffer layers acting either as compliant virtual substrates or as internal stressors able to tune the strain conditions of the GaAsBi layer. This approach enables the growth of GaAsBi layers with similar Bi contents but with different strain conditions varying from compressive to tensile and to grow GaAsBi films with negligible strain for Bi contents as high as 7.2%. These results demonstrate the large potential of strain-engineering concepts for tailoring the optical properties of this material class.