An investigation of near-infrared photoluminescence from AP-MOVPE grown InSb/GaSb quantum dot structures

In this work, the near-infrared photoluminescence (PL) of InSb/GaSb QD structures grown on GaSb substrate (2° off (100)) using atmospheric pressure Metalorganic Vapor Phase Epitaxy is investigated. The structures are analyzed before capping and after capping using scanning probe microscopy and high resolution transmission electron microscopy (HRTEM), respectively. At 10 K, with an excitation power of 2 mW, a PL peak at ∼ 732 meV is observed. Upon an increase in laser power to 120 mW, a blue shift of ∼ 8 meV is noticed. This emission typically persists up to 60-70 K, after which it becomes weak. An SPM analysis of the size distribution of uncapped dots reveals a mono-modal distribution with an average density of ∼ 5×1010 cm−2. However, a HRTEM investigation of the capped dots reveals the formation of an InGaSb quantum well-like structure, ∼ 10 nm thick, which gives rise to the PL signal mentioned above.