Investigation of Localized States in GaAsSb Epilayers Grown by Molecular Beam Epitaxy

Abstract

We report the carrier dynamics in GaAsSb ternary alloy grown by molecular beam epitaxy through comprehensive spectroscopic characterization over a wide temperature range. A detailed analysis of the experimental data reveals a complex carrier relaxation process involving both localized and delocalized states. At low temperature, the localized degree shows linear relationship with the increase of Sb component. The existence of localized states is also confirmed by the temperature dependence of peak position and band width of the emission. At temperature higher than 60 K, emissions related to localized states are quenched while the band to band transition dominates the whole spectrum. This study indicates that the localized states are related to the Sb component in the GaAsSb alloy, while it leads to the poor crystal quality of the material, and the application of GaAsSb alloy would be limited by this deterioration.

Brief Review of Epitaxy and Emission Properties of GaSb and Related Semiconductors

“…For this purpose, using a mixed beam, Wei's group reported the carrier dynamics in GaAsSb ternary alloys grown by MBE. The growth conditions and Sb component of the GaAsSb alloy samples were as those shown in Table 1 [22]. The results indicated that the localized states are related to the Sb component of the GaAsSb alloy; however, this component also leads to poor crystal quality in the material, and the applications of GaAsSb alloys are limited owing to the deterioration in quality.…”

“…However, with the component distribution aggregation effect, the optical properties would exhibit a distinct phenomenon, such as emission related to localized states [22]. Unfortunately, there have only been a few reports on the optical properties of GaAsSb materials [43][44][45][46][47][48][49][50].…”

“…Qiu et al studied the optical spin polarization properties of GaAs 0.94 Sb 0.06 to demonstrate how Sb incorporation modified the spin properties of GaAs [49]. Gao et al focused on the carrier dynamics of GaAs x Sb 1−x epilayers with low Sb content [22]. They discovered the phenomenon of carrier localization, and the degree of localization showed a linear relationship with increasing Sb content.…”

Effect of rapid thermal annealing on the optical properties of GaAsSb alloys

“…GaAsSb was recognized as the important material for fabrication highperformance optoelectronic devices, such as laser diodes, photo-detectors and transistors [5,17,18]. However, the component fluctuations in ternary alloys could cause the localized states in these materials [1,[19][20][21], resulting in carrier localization effect. The carrier localization effect could greatly affect the optical properties of the semiconductors.…”

“…The carrier localization effect could greatly affect the optical properties of the semiconductors. The emission efficiency could be influenced by localized carriers in semiconductor materials, such as GaAsSb, InGaN, GaAsN and MgZnO [19,[22][23][24]. In addition, the optoelectronic performance of devices can also be tuned by manipulating localized states [25,26].…”