Field Dynamics in the Gap of a Semiconductor Nanodimer

Abstract

Semiconductor nanodimer provides substantial terahertz electric field intensification in the gap region as a result of geometric local field effect and surface plasmon resonance. In a dimer formed by two nanoparticles with unequal doping levels, the intrinsic resonances of the nanoparticles are carried over to the coupled configuration of the dimer, giving rise to two resonances, slightly shifted from those of the intrinsic particles. An important characteristic of the enhanced field in the gap is the intensity profile swaying when the frequency of the applied field is varied from one resonance to the other. In this work, the field distribution in an asymmetric semiconductor nanodimer is computed by numerical simulation of the charge-field interaction in the semiconductor, employing a transport formulation for charge dynamics. Charge distribution in the semiconductor, field intensity in the gap and the collective response in terms of the total dipole moment are obtained. Interpretation of the results is presented in light of polarization coupling and interference effects between the particles. Potential application of the dynamical response as a field scanning sensor in the terahertz range is explored.