Electronic structure of self-assembled InGaAs/GaAs quantum rings studied by capacitance-voltage spectroscopy

Abstract

Self-assembled InGaAs quantum rings, embedded in a GaAs matrix, were investigated using magneto-capacitance-voltage spectroscopy. The magnetic-field dispersion of the charging energies exhibits characteristic features for both the first and second electron, which can be attributed to a ground state transition from l=0 into l=−1, and a ground state transition from l=−1 into l=−2, respectively. Furthermore, using a combination of capacitance-voltage spectroscopy and one-dimensional numerical simulations, the conduction band structure of these InGaAs quantum rings was determined.

Quantum Mechanics of Semiconductor Quantum Dots and Rings

“…Only using the geometry followed from Eq. (8) we reproduce result of (Lei et al, 2010), as is shown in Fig. 12.…”

“…The obtained geometry with the parameters m * and  from (Lei et al, 2010) is shown in Fig. 11 (Geometry 2); m *=0.067 0 m and  =15 meV.…”

“…In this section we will show how the effective model works using as an example the CV data. We use results of the CV experiment from Emperador et al, 2000;Lei et al, 2010) for QD and QR.…”

“…Additional energy of an electron in QR in a magnetic field B . The C-V experimental energies (circles) were obtained in (Lei, et al 2010) by using a linear approximation / g Ee V f  , with the lever arm 7.84 f  . The curves 0, 1, 2 l   are the results of our calculations multiplied by a factor of 1.18 (Lei, et al 2010).…”

“…The InGaAs QRs have a height of about 2 nm, an outer diameter of about 49 nm, and an inner diameter of about 20 nm. Also, threedimensional QR geometry (Geometry 2), which follows from the oscillator model (Lei et al, 2010) is used. The confinement of this model is given by the parabolic potential:…”