Effect of As2 flux on the growth of InAs/InGaAs dot-in-well structure by molecular beam epitaxy

This study systematically investigates the growth of InAs/InGaAs dot-in-well (DWELL) structure with a wide range of As₂ flux employed during the growth of InAs dot layer. It is found that As₂ flux plays a very important role in the growth of the DWELL structure, which fundamentally affects the migration length and the desorption rate of In atoms. A non-monotonic variation in the density of InAs quantum dots (QDs) has been observed with varying As₂ flux. In addition, the average width and height of QDs also depends on the As₂ flux. The photoluminescence (PL) peak intensity from the DWELL structure exhibits a remarkable relationship with the As₂ flux, where a maximum intensity enhancement of 90 % was achieved by using the optimized As₂ flux. A total redshift of 58 nm in the peak emission wavelength has been observed within the As₂ flux range studied. Moreover, it has been the first experimental evidence for a distinctive phenomenon that the QDs in the DWELL structure might not be fully capped by the InGaAs layer when the QDs were grown with low As₂ fluxes. Therefore, decomposition of the uncapped portion of QD may occur, resulting in a large blueshift of the PL emission peak from the DWELL structure.