Observation of Excited Biexciton States in CuCl Quantum Dots: Control of the Quantum Dot Energy by a Photon

Abstract

Experimental observations of the excited biexciton states in CuCl quantum dots embedded in a NaCl crystal are presented. An increased absorption due to the transition from the exciton state to the excited biexciton states was clearly observed on the high-energy side of the exciton resonance in subpicosecond pump-and-probe spectra at 77 K. The energy difference between it and the exciton resonance largely increased with decreasing dot size. Temporal evolution of the induced absorption band was studied and the results were consistent with the identification of the excited biexciton states.