Modifying Mie Resonances and Carrier Dynamics of Silicon Nanoparticles by Dense Electron-Hole Plasmas

The strongly localized electric field achieved at the Mie resonances of a silicon nanoparticle enables the generation of a large carrier density, which offers us the opportunity to manipulate the linear and nonlinear optical properties of silicon nanoparticles by optically injecting a dense electron-hole plasma. Here, we show that the dense electron-hole plasma created in a silicon nanoparticle significantly modifies the complex dielectric constant of silicon, which in turn leads to wavelength shift and amplitude change in the magnetic dipole resonance. We demonstrate that the maximum wavelength shift of the magnetic dipole resonance can be revealed by exploiting the hot-electron luminescence emitted by the silicon nanoparticle, which acts as a built-in light source with a broad bandwidth and a short lifetime. We demonstrate that the quantum efficiency of the hot-electron luminescence of silicon nanoparticles can be enhanced a factor of more than 5 through the injection of a dense electron-hole plasma. More interestingly, an acceleration of the radiative recombination process is found at high carrier densities. Our findings are helpful for understanding the modification of Mie resonances in silicon nanoparticles induced by the dense electron-hole plasmas and useful for designing silicon-based photonic devices.