Abstract:
Controlling the light transport using photonic structures is essential for the deterministic control of light trapping
and that depends on the nano-scale spatial modulation of refractive index. Here, we study the optimal effective
refractive index profile (neff) of vertically-aligned disordered silicon nanowires using the measured spatial-and
wavelength-dependent micro-reflectivity values across the nanowire length. A multi-layer model for the nanowire
sample is employed to calculate the reflectivity values using the different neff profiles. The calculated
reflectivity values are compared with the measured reflectivity values for different polarization states of light.
The results validate that the silicon nanowires with an exponential neff profile suppress more than 90% reflectivity
over a wide angular range for both polarization states of light. Moreover, the nanowires sample with an
exponential neff profile shows a significant enhancement in light trapping and Raman scattering.
