Pressure effect on an exciton in a wurtzite AlN/GaN/AlN spherical core/shell quantum dot
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Research Letter
Pressure effect on an exciton in a wurtzite AlN/GaN/AlN spherical core/ shell quantum dot N. Aghoutane, M. El-Yadri, and E. Feddi, LaMCScI, Group of Optoelectronic of Semiconductors and Nanomaterials, ENSET, Mohammed V University in Rabat, Rabat 10100, Morocco F. Dujardin, LCP-A2MC, Institut de Chimie, Physique et Matériaux, Université de Lorraine, F-57000 Metz, France M. Sadoqi, Department of Physics, St. John’s College of Liberal Arts and Sciences, St. John’s University, Jamaica, NY 11439, USA; Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John’s University, Jamaica, NY 11439, USA G. Long, Department of Physics, St. John’s College of Liberal Arts and Sciences, St. John’s University, Jamaica, NY 11439, USA Address all correspondence to Elmustapha Feddi and Gen Long at [email protected] and [email protected] (Received 25 January 2018; accepted 10 April 2018)
Abstract We have studied the effect of hydrostatic pressure on the confined exciton in a spherical core–shell quantum dot. Using a simple variational approach under the framework of effective mass approximation, we have computed the excitonic binding energy as a function of the shell thickness under the applied hydrostatic pressure. Our results show that the ground state binding energy of exciton depends greatly on the shell thickness, which tends to the two-dimensional limit of 4RX, when the ratio a/b tends to unity. The numerical calculations also suggest that the applied hydrostatic pressure favors the attraction between electrons and holes so the excitonic binding energy increases when pressure increases.
Introduction Recently, the advance in material science and materials growth methods renders the possibility to produce a new generation of heterostructures called core/shell quantum dots (CSQD), composed of different geometrical shapes and material compositions.[1–4] They are typically composed of two semiconductor materials with different band gaps: the core is made with a material with smaller bulk band gap, and the shell is made with a material of the larger band gap (Fig. 1). The advantage of these nanostructures is the possibility of controlling the material properties of the CSQDs by varying their sizes/thickness, and hence realizing the manipulation of their energy levels, as well as the intra- or inter-band transitions through absorption or emission. In the literature, a great deal of studies has been realized for these (CSQDs).[1,2,5,6] From these works, we can conclude that these nanostructures have shown interesting physical properties, through redistribution of the electron and hole wave functions, such as the energy dependence of the core/shell radii ratio, an increase in the band-edge absorption for small band gap shell material, and a drastic change in the intensity of the luminescence. It is widely accepted that the confinement of excitons in semiconductor nanostructures gives an increased excitonic effect in their band gaps, which is more desirable in the design of novel photoelectric
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