Abstract

We have studied the luminescence of CdTe semiconductor quantum dots (SQD) and have shown that the structure of their luminescence spectrum near the band edge is due to the size distribution of the quantum dots. Usually the luminescence spectrum of II-VI SQD consists of two bands: the narrow "edge luminescence" (EL) band influenced by quantum confinement phenomena (near the band edge) and the broad luminescence band induced by deep energy levels. Recently the broadening and the appearance of the additional structure of the high energy wing of the EL of CdS and CdSe SQD has been reported and explained through hot luminescence under high intensities of excitation and state filling process [1, 2]. Also it was assumed that the observed structure is the result of the excitation of nanocrystals of two different sizes by the same wavelength [3]. However other researchers did not observe the structure. This indicates the fact that the phenomenon is sample dependent. Here we present the detailed investigation of the EL of the samples embedded with CdTe SQD with wide size distribution. It is shown that the observed structure of the luminescence is due to the luminescence of the SQD of different size.

© 1998 IEEE