Evidence of excited levels in self-organized InAs/InP(001) islands with low size dispersion

Self-organized InAs quantum islands (QIs) with low size dispersion have been fabricated on InP(0 0 1) substrate using Stranski-Krastanov growth mode. The degree of linear polarization of about 28% indicates the elaboration of InAs QIs elongated in the [1-10] direction. Photoluminescence excitation (PLE) measurements show that the multi-component PL spectrum is attributed to emission coming out from transitions assigned to ground and related excited states of the InAs QIs. This attribution has been confirmed by time resolved PL measurements which allow to compare the dynamics of the ground state with those of the excited states. A value of 22 meV at 8 K for the full-width at half-maximum of the ground state PL peak is measured confirming the narrow island size distribution. The total integrated PL intensity decreases only by a factor about two when increasing temperature from 8 to 300 K, indicating a strong spatial localization of the excitons in these InAs QIs. (C) 2002 Elsevier Science B.V. All rights reserved.