Structural, optical and intraband absorption properties of vertically aligned In0.32Ga0.68As/GaAs quantum dots superlattices

The self-organization growth of In_0.32Ga_0.68As/GaAs quantum dots (QDs) superlattices is investigated by molecular beam epitaxy. It is found that high growth temperature and low growth rate are favorable for the formation of perfect vertically aligned QDs superlattices. The aspect ratio (height versus diameter) of QD increases from 0.16 to 0.23 with increase number of bi-layer. We propose that this shape change play a significant role to improve the uniformity of QDs superlattices. Features in the variable temperature photoluminescence characteristics indicate the high uniformity of the QDs. Strong infrared absorption in the 8–12 μm was observed. Our results suggest the promising applications of QDs in normal sensitive infrared photodetectors.