Neutral and charged excitons in a quantum tube

Abstract

The optical transition energies of neutral and charged excitons in a quantum tube are calculated as a function of the Aharonov-Bohm magnetic flux Φ. The oscillation amplitude of the ground state energy of the electron-hole relative motion is shown to be larger in a quantum tube than a quantum ring with strong confinement in the axis direction. We find a double maxima structure in the optical transition energy for a quantum tube with radius R=0.5 in units of the effective Bohr radius because of the difference in the Φ dependencies between the single electron energy and the relative motion energy of a charged exciton state.

Aharonov–Bohm Oscillations in Photoluminescence from Charged Exciton in Quantum Tubes

“…In contrast to the previous reports on InGaAs quantum rings 4 or InP type-II QDs, 6 no quadratic shift in the PL transition energies with magnetic field is observed. This is exactly what is expected for a quantum ring 2, 3 or a quantum tube 11 with a single channel surrounding the magnetic flux.…”

“…18 The Hamiltonian of a X − state is separated into the center-of-mass motion (H c.m. ) and the relative motion with respect to a hole (H rel ) 5,11,15 as given by H = H c.m. + H rel ,…”

“…It should be noted that the oscillation of the optical transition energy with a period of φ 0 without diamagnetic shift is only expected for an infinitesimally thin quantum tube. 11 In a quantum ring with infinitesimally small width, the amplitude of AB oscillation would be zero because of the divergence of the Coulomb interaction, and in a quantum ring with a finite width, the exciton ground state shows a quadratic shift with magnetic field. 19 Although our calculation is simple, the results capture the essential features of the observed oscillation of PL energy.…”

“…13,14) The ground state energy and wave function are obtained by the numerical diagonalization of the Hamiltonian matrix as described in detail elsewhere. 11) The calculated result is shown in Fig. 4(a).…”

Semiconductor quantum tubes: Dielectric modulation and excitonic response

“…Present work on QTs theoretically considered magnetic states, 24,25 reported experimental evidence of the Aharonov-Bohm effect, 26 and treated optical properties, 27 but the influence of the dielectric dismatch between the nanostructure and the environment has been studied so far only for conventional quantum wires 21 and freestanding nanowires. 20 Here we will consider also a dielectric mismatch between the core and the shell, which will lead to a considerable change in the electron-hole interaction, as shown in Fig.…”