Characterization of multi-interface, multi-layer, heavily doped Si:P nanostructures using electromagnetic propagation

Layered semiconductor structures like delta-dopings and buried amorphizations, where modified optoelectronic features result simultaneously from material composition and device design, can considerably widen optoelectronic applications of conventional materials. Multi-interface novel devices (MINDs) based on a nanoscale Si-layered system buried within a heavily P-doped Si wafer show an unusual reflection, absorption and internal light propagation, which can be dominated by a dense free-carrier gas confined within the surface potential well. First, to simulate the electromagnetic optical response and field propagation, a model of optical functions of the heavily doped Si: P using the Transition Matrix Approach has been constructed. The model uses experimental data published previously for extremely heavily P-doped Si. The dielectric function combines oscillation functions and a dense free-carrier gas (Lorentz-Drude approach) while respecting an inhomogeneous P-doping distribution. Next, an optical model of the real multi-interface device, based on electron microscopy data, has been adapted. A simplified sequence of buried optically active interfaces and corresponding layers (with transformed material and specific refraction indexes) is possible due to a planar (1D) geometry. Finally, the comparison of simulated and experimental reflectivity validates our model.