Analysis of optical properties and reduced stain estimation in InAs/InGaAsSb quantum dot heterostructure with the variation of growth rate

Conventional InAs/GaAs QD heterostructures are drawing the significant amount of interest among the worldwide researchers due to the excellent carrier confinement, high optical absorption, lower binding energy and high electron mobility. Also, impact of Sb incorporation in the capping layers provides the far-infrared wavelength emission window (1.3 μm to 1.56 μm). In current work, the effects of strain and composition on the optical properties of vertically uncoupled InAs/InGaAs quantum dots (QDs) capped with a thin layer combining Sb quaternary alloys are investigated experimentally. In this work, growth rate of the QDs formation is varied such as 0.05 ML/s, 0.07 ML/s and 0.1 ML/s for selective 28% Sb composition. The atomic force microscopic (AFM) measurement is performed on the grown quaternary capped QDs heterostructures and better dot uniformity and density is observed for selective growth rate sample. The out-plane X-ray diffraction (XRD) is measured for all the growth rate varying heterostructures. The strains are estimated from the corresponding XRD plots and such results confirm the defect free growth of heterostructures with reduced strain and high dot size for 0.05 ML/s growth rate sample. The photoluminescence (PL) is conducted to characterize the optical properties of the grown QDs heterostructures. The 20 K PL peak is gradually shifted from 1214 nm to1249 nm with the decreasing growth rate from 0.1 ML/s to 0.05 ML/s. Therefore, growth rate is optimized for InAs/InGaAsSb QD heterostructures, which will be exhibited the higher photo absorption and carrier lifetime and such heterostructures can be a promising candidate for III-V QD based opto-electronic devices.