Effect of exciton transfer on recombination dynamics in vertically nonuniform GaAsSb epilayers

Abstract

Low-temperature photoluminescence (PL), photoreflectance (PR), and temperature dependent time-resolved PL spectroscopies are employed to investigate optical emission processes and exciton dynamics in graded GaAsSb epilayers. The nonuniformity in the Sb composition along the growth direction is disclosed from low-temperature PL and PR measurements. Furthermore, significant differences in PL dynamics are found at low temperatures for the PL emissions originating from spatial regions with the low and high Sb compositions, with a fast decay and a slow rise at the early stage of the PL transient, respectively. This finding is attributed to exciton transfer from the low Sb region to the high Sb region. The obtained results are important for a general understanding of optical transitions and exciton/carrier dynamics in material systems with graded alloy composition.

Lattice‐Optimized GaAsSb/InP Heterojunction Toward Both Efficient Carrier Confinement and Thermal Dissipation

“…It is interesting to note in Figure d that there also exists an S shape of the PL peak position as a function of excitation laser power for S1 (Sb = 37.7%) and S3 (Sb = 56.2%) samples. This behavior is different from previous studies focused on power‐dependent PL measurements in the III–V alloy system, which always reveals a blueshift of the PL peaks as an increase in excitation laser power . This initial blueshift has been ascribed to the band filling of the localized states and the carriers will fill in high‐energy levels with a high excitation laser power .…”

“…The emission efficiency and the electron spin lifetime could be influenced by localized carriers . Thus it is important to have a deeper understanding of the localization state of GaAsSb.…”

“…The emission efficiency and the electron spin lifetime could be influenced by localized carriers. [11][12][13][14] Thus it is important to have a deeper understanding of the localization state of GaAsSb. However, most investigations have focused on the carrier localization in GaAsSb epilayers grown on GaAs with limited Sb concentrations less than %13%, which indicates that as the Sb composition increases, the degree of the localization state increases as well.…”

“…an increase in excitation laser power. [11,13,18,25] This initial blueshift has been ascribed to the band filling of the localized states and the carriers will fill in high-energy levels with a high excitation laser power. [8] At a higher excitation, localized states will be eventually saturated and the emission peak will reach the maximum position.…”

Self-assembled nanodisks in coaxial GaAs/GaAsBi/GaAs core–multishell nanowires

“…The use of ternary compounds, however, is typically accompanied by complicated alloy fluctuations 23,24 and even self-induced compositional gradient along the growth direction due to phase separation. 25 Local changes in the composition necessarily cause spatial variations in the electronic structure and, therefore, the formation of a localization potential within nanowires. Though somewhat detrimental for transport properties, the localization effects create new possibilities for fabrication of self-assembled nanostructures.…”