Few-particle effects in single CdTe quantum dots

Optical emission from individual, n-type modulation-doped CdTe quantum dots (QD’s) is presented. Magnetomicrophotoluminescence and power-excitation-dependent measurements allows one to identify the neutral exciton, the negatively charged exciton, and the biexciton. All these few-particle species are exposed to randomly fluctuating electric fields attributed to charges trapped in the vicinity of the QD. The resulting quantum confined Stark effect, characteristic for each quantum dot, is analyzed in detail. The correlations between the emission energies of the neutral and charged exciton as well as between their integrated intensities confirm the identification of the charged species. The binding energies of the biexciton and charged exciton decrease sharply with the magnitude of the local electric field.