Luminescence Decay in Deep Quantum Wells CdTe/Cd_0.5Mn_0.5Te at Room Temperature

Abstract

Time-resolved photoluminescence was used to study exciton recombination in deep CdTe/Cd0.5Mn0.5Te single quantum well. The width of the investigated well was 100 A. The study was performed at room temperature. The lifetime of the exciton determined in this work has a value comparable to that observed in shallow CdTe/Cd0.85Mn0.15Te quantum wells. A strong enhancement of the photoluminescence decay time with increasing intensity of the exciting laser beam is observed which is indicative of saturation of the non-radiative recombination centers. PACS numbers: 78.55.Et, 78.66.Hf Time dependence of the luminescence intensity from quantum wells made of CdTe surrounded by Cd1-x Mnx Te barriers was subject of several studies [1][2][3][4]. Most of them dealt with relatively shallow wells corresponding to MnTe molar fraction in the barrier material that did not exceed x = 0.3. The interest in the time resolved luminescence studies originates in a need for precise information about the details of the nature of excitonic states which give rise to luminescent properties of heterostructures made of CdTe/Cd1-x Mnx Te system and their predominant recombination mechanisms. Additional motivation for this type of studies is provided by the fact that the system consists of magnetic barriers which may give rise to a formation of either free or bound excitonic magnetic polarons in non-magnetic CdTe quantum wells [5,6]. This, in turn, can be related to, e.g., a localization of the excitonic wave functions in the vicinity of the interfaces [7,8]. Study of the dynamics of the recombination processes can also shed light on the relevant mechanisms of the formation of magnetic phases observed in the material.The present communication reports on a study of the decay time of the luminescence from very deep CdTe/Cd1-x Mnx Te quantum wells. The composition of the barrier in the sample studied by us corresponded to MnTe molar fraction (508)