上海科技大学知识管理系统

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.