Optical properties of InAs quantum dots: Common trends

Abstract

We compare results obtained in several tens of samples grown by molecular-beam epitaxy under different growth conditions with a substantial amount of data found in the literature. By plotting the photoluminescence (PL) peak energy ${(E}_{p})$ of the quantum dot (QD) bands as a function of the nominal thickness of deposited InAs (L) three regions are clearly evidenced in the ${(E}_{p},L)$ plane. Below the so-called critical thickness ${(L}_{c}),$ three-dimensional precursors of QD's show a smooth dependence of their emission energy on L. Around ${L}_{c},$ QD's show a steep dependence of ${E}_{p}$ on L, independent of the growth conditions. Finally, for $L\ensuremath{\gtrsim}2$ ML one observes a saturation of the PL energy. This energy assumes only discrete values dependent on the growth conditions, which is attributed to the aggregation of quantum dots with different faceting.