Electron confinement in nanocrystals embedded in random media: Anderson localization effects

摘要

The effect of Anderson localization of electrons in nanocrystals (NC's) embedded in an amorphous matrix of the same semiconductor material is investigated. A simple condition of localization in the disorder potential produced by the amorphous matrix around a perfectly crystalline core is formulated, determined by the reflection from the inhomogeneous random barrier at the NC/matrix interface. It is found that there are confined states in the NC's, arising from an almost complete reflection of the electron wavefunction by the barrier, which can be characteristic of either strong or weak localization. The local density of states has been calculated numerically using parameters of Si NC's embedded in amorphous silicon, which contains information concerning the states confined in the NC's. These states, with energies depending on the NC size, are resonant and have a lifetime decreasing with the increase of the energy.