Energy spectrum and adapting the transmission coefficient of excitons in core–shell GaAs/AlxGa1-xAs spherical and cubic quantum dots

Abstract

This study investigates the quantum size effect on the energy spectrum of the exciton as a charge carriers confined in a core–shell of spherical and cubic GaAs/Al_xGa_1-xAs quantum dots with finite potential barrier specified as a function of the doping material. The calculations indicated the inverse relationship between the confinement energy values of the first three energy levels and the dot volumes. In comparing the energy levels of the two shapes, results indicated that the energy values for the first two levels of the spherical dot are lower than those for the cubic one, however for the third level the energy of the spherical dot is larger than that for the cubic dot. Tunneling effects are studied by calculating the transmission coefficient related to each energy level. The results exhibited that larger values correspond to the excitons in the second excited state and small dot volumes. Additionally, increasing the doping values enhanced decreases in the transmission coefficient values. Finally, calculation to the wavelength of the emitted light from the ground state energy level illustrated that the emitted wavelengths more precisely affected by the dot compositions. The emitted light wavelength from the ground state energy level is also examined. For x = 0.2, the emitted wavelengths range from 658.7 to 721.8 nm for spherical Quantum dots and 649.5 to 720.3 nm for cubic Quantum dots across all volumes. For x = 0.4, the emitted wavelengths fall within the yellow light range (571–586.6 nm) for small Quantum dots (125–216 nm³), the orange light range (597.9–624.8 nm) for medium-sized Quantum dots (343–1728 nm³), and the red-light range (627.4–631.2 nm) for larger Quantum dots (2197–3375 nm³). These findings contribute to the development of more efficient optoelectronic devices and quantum computing components by providing insight into quantum confinement and light emission properties in nanostructured materials.