Density control of InP/GaInP quantum dots grown by metal-organic vapor-phase epitaxy

We investigated structural and emission properties of self-organized InP/GaInP quantum dots (QD) grown by metal organic chemical vapor deposition using an amount of deposited In from 7 to 2 monolayers (ML). In the uncapped samples, using atomic force microscopy (AFM), we observed lateral sizes of 100–200 nm, together with a bimodal height distribution having maxima at $\sim$5 and $\sim$15 nm, which we denoted as QDs of type $A$ and $B$, respectively; and reduction of the density of the type-$B$ dots from 4.4 to 1.6 $\mu$m$^{-2}$. The reduction of the density of $B$-type dots were observed also using transmission electron microscopy of the capped samples. Using single dot low-temperature photoluminescence (PL) spectroscopy we demonstrated effects of Wigner localization for the electrons accumulated in these dots.