Carrier diffusion in semiconductor nanoscale resonators

TL;DR

This paper demonstrates that semiconductor nanoscale resonators with extreme dielectric confinement significantly accelerate carrier diffusion, potentially enabling faster optical switches, and introduces an efficient eigenmode expansion technique to analyze the diffusion process.

Contribution

It introduces an eigenmode expansion method to analyze carrier diffusion in nanoscale resonators, revealing the impact of cavity geometry on diffusion dynamics.

Findings

Eigenmode approach captures long-timescale carrier decay effectively.

Cavity geometry influences in-plane and out-of-plane diffusion contributions.

Resonators with dielectric confinement can enhance optical switching speeds.

Abstract

It is shown that semiconductor nanoscale resonators with extreme dielectric confinement accelerate the diffusion of electron-hole pairs excited by nonlinear absorption. These novel cavity designs may lead to optical switches with superior modulation speeds compared to conventional geometries. The response function of the effective carrier density is computed by an efficient eigenmode expansion technique. A few eigenmodes of the diffusion equation conveniently capture the long-timescale carrier decay rate, which is advantageous compared to time-domain simulations. Notably, the eigenmode approach elucidates the contribution to carrier diffusion of the in-plane and out-of-plane cavity geometry, which may guide future designs.