Effects of shape on the far-infrared absorption of quantum dots

Ingibjörg Magnúsdóttir
Science Institute, University of Iceland,
IS-107 Reykjavik, Iceland.
e-mail:ingibjm@raunvis.hi.is

Quantum dots are small electron systems, a few nanometers in diameter, realized by means of modern fabrication techniques. Their energy spectrum is discrete, due to confinement of the electrons in all three dimensions. The typical energy level spacing lies in the range of a few meV, i.e. within the far-infrared (FIR) range of the electromagnetic spectrum. In this master's thesis, the FIR absorption of electrons in quantum dots of circular, elliptic and square shape, is calculated, focusing on two electron dots. Their mutual Coulomb interaction is evaluated in the Hartree approximation. Calculation results are compared to available experiments. The statement of the generalized Kohn theorem is confirmed for the circular and elliptic dots, i.e. that FIR only couples to the center-of-mass motion of the electrons. For square symmetric dots, it no longer applies, and relative motion of electrons is also induced. Traces of the Coulomb interaction are identified in the absorption spectra of such dots.