Excitonic nonlinear optical properties in AlN/GaN spherical core/shell quantum dots under pressure
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Research Letter
Excitonic nonlinear optical properties in AlN/GaN spherical core/shell quantum dots under pressure N. Aghoutane, M. El-Yadri, A. El Aouami, and E. Feddi, Laboratoire de Matière Condensée et Sciences Interdisciplinaires (LaMCScI), Group of Optoelectronic of Semiconductors and Nanomaterials, ENSET, Mohammed V University in Rabat, Rabat 10100, Morocco G. Long , and M. Sadoqi, Department of Physics, Saint John’s University, Jamaica, NY, 11439, USA F. Dujardin, LCP-A2MC, Université de Lorraine, 57000 Metz, France Chuong V. Nguyen, Department of Materials Science and Engineering, Le Quy Don Technical University, Hanoi, 100000, Vietnam Nguyen N. Hieu, Institute of Research and Development, Duy Tan University, Da Nang, 550000, Vietnam Huynh V. Phuc, Division of Theoretical Physics, Dong Thap University, Cao Lanh, 870000, Vietnam Address all correspondence to E. Feddi at [email protected]; G. Long at [email protected] (Received 23 January 2019; accepted 26 March 2019)
Abstract This work is based on a recent theoretical study of how the hydrostatic pressure and core/shell sizes affect the optical properties associated with the transition from the ground state to first excited state (1s–1p), of an exciton confined in spherical core/shell quantum dots (SCSQDs). We have computed under an effective mass framework, linear, third-order nonlinear, and total absorption coefficients (AC) and refractive index (RI) as functions of photon energy for different sizes of SCSQDs with varying hydrostatic pressure. Our results show that the optical absorption is deeply dependent on the incident light intensity. Both AC and RI significantly influenced by the confinement and pressure effects.
Introduction In recent years, thanks to advance in nanomaterial growth and characterization, spherical core/shell quantum dots (SCSQDs) have been widely realized on various material systems and extensively studied experimentally and theoretically.[1–5] These nanostructures usually consist of an inorganic material (core), which is covered by a layer of another material (shell) with a band gap lower than that of the core (i.e., reverse type-I). The nanostructures can be coated with another material (usually organic molecules as ligands) which stabilizes these nanostructures via the passivation of their surfaces thus prevent their physical degradation and ensure their optical properties. The novel properties of these nanoscale structures arise from quantum confinement effects, and therefore they draw great interest in nanomaterial research community due to their potentially wide variety of applications such as photovoltaics,[6,7] light-emitting diodes,[8–10] and nonlinear optics.[11] Many studies have been realized for SCSQDs.[12–18] From these results we can conclude that these nanostructures acquire interesting physical properties, such as the enhanced binding energy due to strong confinement when the hydrostatic pressure and magnetic field are applied, plus increased band-edge absorption for small band gap shell materials, as well as the enhance
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