Optical properties of InAs quantum dots: Common trends

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 (Eₚ) of the quantum dot (QD) bands as a function of the nominal thickness of deposited InAs (L) three regions are clearly evidenced in the (Eₚ,L) plane. Below the so-called critical thickness (Lc), three-dimensional precursors of QD's show a smooth dependence of their emission energy on L. Around Lc, QD's show a steep dependence of Eₚ on L, independent of the growth conditions. Finally, for L2 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.