Experimental determination of electron and hole sublevels in modulation-doped InAs/GaAs quantum dots

Electron and hole sublevels in quantum dots (QDs) are experimentally determined using the excitation-power dependence of photoluminescence spectrum for a modulation-doped QD structure. The sublevel spacing between n=1 and n=2 electron states can be obtained from the photoluminescence (PL) spectrum under very low excitation and the spacing between n=1 and n=2 hole states can be obtained by comparing the PL spectrum under high excitation with the one under low excitation. The proposed method should give useful information in the design of QD devices, as well as for the verification of theoretical calculations of QD energy levels.