NARROW PHOTOLUMINESCENCE LINE-WIDTH OF CLOSELY STACKED INAS SELF-ASSEMBLED QUANTUM-DOT STRUCTURES

We report an effect of interval layer thickness in stacked InAs self-a ssembled quantum dot (QD) structures on photoluminescence (PL) charact eristics focusing on thicknesses less than 3 nm. A drastic decrease in PL line width as narrow as 21 meV at 4.2 K was obtained with 2-nm int erval layers. PL measurements show that the stacked structure forms an equivalent single QD structure which vertical size is extended effect ively more than that of single layer QD. This attributes to the decrea se of PL line width governed by the fluctuation mainly in the vertical direction. PL from higher order quantized states up to the 4th state are also clearly observed.