Electron energy relaxation in silicon quantum dots by acoustic and optical phonon scattering

In the present work, we theoretically investigate the energy relaxation of electrons due to acoustic and optical phonon scattering in quantum-dot systems embedded in a Si metal-oxide-semiconductor structure with (100) surface orientation. The confinement potential normal to the Si/SiO₂ interface is modeled by an infinite triangular quantum well. For the spatial confinement in the lateral directions due to depletion gates we assume a parabolic potential. The calculated transition rates for electron scattering between discrete energy levels in the dot are included in a simple transport model using Monte Carlo techniques to simulate the relaxation of electrons from higher levels back to the ground level. We find that the electron decay shows a non-exponential behavior. The simulated relaxation time strongly depends on the confinement in the lateral directions and may vary by several orders of magnitude.