[en] We analyze the microstructure of a series of Ga(Sb, Bi)/GaSb quantum wells (QW) with varying Bi content and QW thicknesses using transmission electron microscopy. The structures are grown on GaSb(001) substrates by low-temperature molecular beam epitaxy. Although Ga(Sb, Bi) is regarded as a highly-mismatched alloy, the material is of remarkable quality and no extended defects or nanoclusters are detected in the pseudomorphic layers. Regardless their different Bi content (ranging from 4% to 11%) all QW samples seem to be homogeneous in composition and no composition fluctuations are detected. The QW/barriers are nevertheless affected by thickness fluctuations, where the thickness slightly varies from QW to QW but also laterally. Despite the samples exhibit well-defined QW/barrier interfaces, we note that the Ga(Sb, Bi)-on-GaSb interface is rougher than the GaSb-on-Ga(Sb, Bi) one. The morphological smoothing effect at the GaSb-on-Ga(Sb, Bi) interface is attributed to the well-known surfactant behavior of Bi in connection with Bi surface segregation, as evidenced from experimental Bi distribution profiles. (paper)

[en] Optical properties and carrier dynamics in 6.6, 10.4, and 14.4 nm wide Ga(Sb, Bi)/GaSb quantum wells (QWs) with ∼10%–11% of Bi were studied by photoluminescence (PL), time-resolved PL, and transient reflectivity. Experiments revealed that low temperature emission is strongly governed by the decay of excitonic population that undergoes weak localization on the QW potential fluctuations rather than the strong defect-like localization typically found for highly mismatched alloys. This statement is supported first by the nearly linear increase of the PL intensity with the excitation power, second, by the lack of the S-shape signature in the temperature-dependent PL studies, and third, the absence of a strong lifetime dispersion for excitons. The low-temperature intraband carrier relaxation time is established in the range of 14–19 ps, nearly independent on the well width, while the exciton lifetime exhibits a well width dependence, i.e. this time decreases from ∼265 ps, through ∼206 ps, to ∼147 ps with the increase of the QW width from 6.6 to 14.4 nm. Our results demonstrate that in contrast to other dilute bismide alloys, GaSbBi behaves as a regular alloy rather than as a highly-mismatched material. (paper)