Effect of magnetic field, size and donor position on the absorption coefficients related a donor within the core/shell/shell quantum dot

In this study, linear, nonlinear and total optical absorption coefficients related a single shallow donor atom confined in semiconductor core/shell/shell quantum dot heterostructure are researched in detail within the compact density matrix formalism approximation. For this purpose, firstly, the energies and the wavefunctions are computed by the diagonalization method in the effective mass approach. Moreover, the effects of size modulation, donor position and magnetic field are analyzed. The numerical results indicate that the linear and nonlinear parts of the absorption coefficients related with intersubband 1s-1p and 1p-1d donor transitions undergo significant changes.

Electronic property and charge carrier mobility of one-dimensional nanowires consisting of C20 cages

This work presented theoretical studies on the one-dimensional (1D) nanowires constructed from fullerene C20 cages based on first-principle calculations. The relative energies, electronic, charge transport, and mechanical properties of the 1D nanowires were investigated systemically and in detail. It is found that formations of the C20 nanowires built from isolated cages were all energetically favorable. They also exhibit high kinetic stability according to molecular dynamics simulations. Although they were all constructed with C20 cages as building blocks, NW-2–NW-6, and NW-9 are semiconductors, whereas NW-1, NW-7, and NW-8 exhibit metallic property. Thus the metallic/semiconducting properties of the 1D C20 nanowires can be mainly determined by the connecting patterns. High charge mobility was revealed for the 1D C20 nanowires based on the deformation potential theory and effective mass approach. Further understanding of the charge mobility is achieved with the aid of crystal orbital analyses. Moreover, the mechanical property of the 1D C20 nanowires was also studied based on the results of Young’s modulus.

Electron position: jumping in double concentric quantum rings

ABSTRACTSemiconductor heterostructures as quantum dots or quantum rings (QR) demonstrate discrete atom-like energy level structure. In an atom the position of an electron can be changed by electromagnetic field influence with accompaniment of quantum number change. In present work we show that in the weak coupled Double Concentric Quantum Ring (DCQR), the electron jumping is possible due to tunneling accompanied with level anti-crossing which has a place in a magnetic field. We study DCQR composed of GaAs in an Al0.70Ga0.30As substrate under influence of a magnetic field. In our model the DCQR is considered within three dimensional single sub-band effective mass approach. When a magnetic field is applied in the z direction, perpendicular to the DCQR plane. The results of the numerical calculations for DCQR are presented for DCQRs of different geometry.