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Title: Dynamics of bound exciton complexes in CdS nanobelts
Authors: Xu, X.
Zhao, Y.
Sie, E.J.
Lu, Y. 
Liu, B.
Ekahana, S.A.
Ju, X.
Jiang, Q.
Wang, J.
Sun, H.
Sum, T.C.
Huan, C.H.A.
Feng, Y.P. 
Xiong, Q.
Keywords: Bound exciton complex
CdS nanobelt
Dynamics defect level
Exciton interaction
Issue Date: 24-May-2011
Citation: Xu, X., Zhao, Y., Sie, E.J., Lu, Y., Liu, B., Ekahana, S.A., Ju, X., Jiang, Q., Wang, J., Sun, H., Sum, T.C., Huan, C.H.A., Feng, Y.P., Xiong, Q. (2011-05-24). Dynamics of bound exciton complexes in CdS nanobelts. ACS Nano 5 (5) : 3660-3669. ScholarBank@NUS Repository.
Abstract: Intrinsic defects such as vacancies, interstitials, and anti-sites often introduce rich luminescent properties in II-VI semiconductor nanomaterials. A clear understanding of the dynamics of the defect-related excitons is particularly important for the design and optimization of nanoscale optoelectronic devices. In this paper, low-temperature steady-state and time-resolved photoluminescence (PL) spectroscopies have been carried out to investigate the emission of cadmium sulfide (CdS) nanobelts that originates from the radiative recombination of excitons bound to neutral donors (I2) and the spatially localized donor-acceptor pairs (DAP), in which the assignment is supported by first principle calculations. Our results verify that the shallow donors in CdS are contributed by sulfur vacancies while the acceptors are contributed by cadmium vacancies. At high excitation intensities, the DAP emission saturates and the PL is dominated by I2 emission. Beyond a threshold power of approximately 5 μW, amplified spontaneous emission (ASE) of I2 occurs. Further analysis shows that these intrinsic defects created long-lived (spin triplet) DAP trap states due to spin-polarized Cd vacancies which become saturated at intense carrier excitations. © 2011 American Chemical Society.
Source Title: ACS Nano
ISSN: 19360851
DOI: 10.1021/nn2008832
Appears in Collections:Staff Publications

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