Temperature Dependent Luminescence of CdSe Quantum Dots of Different Structure

摘要

Temperature dependence of photoluminescence (PL) of quantum dots (QD's) is the mater that has been widely studied in recent literature. Three-dimensional carrier confinement leading to the δ-like density of states makes thermal behaviour of QD's emission drastically different from that for bulk material. Characteristic features of this behaviour are: 1) quenching, which begins at relatively high temperatures, attributed to thermal escape of carriers from the ground state of dots into the barrier material or wetting layers directly or through the ladder of exited states; 2) abnormal variation of peak position and full width at half maximum (FWHM) which is counted to be caused by tunnelling and thermal redistribution of carriers between the dots of different sizes. Therefore, besides the obvious practical importance connected to the realization of room temperature efficient devices, the investigation of temperature dependence of QD's emission, which gives the information about the mechanisms of the mentioned processes, is also very interesting in fundamental point of view. In this paper we study temperature dependent luminescence of different samples containing CdSe/Zn (S, Se) QD's.