A continuous and systematic red shift of the exciton emission energy in small InP/InGaP quantum dots is observed for increasing excitation energies and intensities. Superposed on this red shift, emission energy minima appear which show a one-to-one correspondence to emission intensity maxima as a function of the excitation energy. This band-gap renormalization is attributed to the hybridization of the quantum dot excited states with the wetting layer continuum. Polarization-resolved measurements reveal that the exciton fine structure splitting can be tuned up to 10% in the present case by changing the excitation energy. Possible implications of the present results on the development of entangled photon pair sources are discussed.

This work has been supported by research contracts of the Spanish Ministry of Education Grants MAT2008-01555/NAN, TEC2008-06756-C03-01, and Consolider CSD 2006-19, and the Community of Madrid CAM (P2009/ESP-1503).

5 figuras, 5 páginas.-- PACS number(s): 78.67.Hc, 78.55.Cr

P2009/ESP-1503/Q&CLight

Peer reviewed