The energy level spacing from InAs∕GaAs quantum dots: Its relation to the emission wavelength, carrier lifetime, and zero dimensionality

Abstract

We have found that the level spacing between the ground and first excited states of InAs∕GaAs quantum dots (QDs) increases as the photoluminescence peak energy decreases, that is, as the QD increases in size. By means of simple numerical calculations, we confirm that this seemingly unusual level-spacing behavior originates from the low aspect ratio of typical QDs with a finite potential barrier. Carrier lifetime measurements show that QDs with a lower photoluminescence peak energy tend to have a shorter decay time, which can be attributed to better confinement of the electron wave function and the resultant increase in electron-hole wave function overlap.