Design and optimization of antireflecting coatings from nanostructured porous silicon dielectric multilayers

• Optimized optical response is analyzed theoretically/experimentally for Si ARCs.
• Optimal thickness of the antireflecting structure was computed to be 235 nm.
• Average reflectance for optimized structure was measured to be 1.3%.

We report the design and fabrication of an optimized antireflecting structure with the maximum transmittance (Tmax) and minimum reflectivity (Rmin), based on a porous silicon dielectric multilayer (PS-DM). The structures consist of 50 layers of equal thicknesses with an increasing refractive index profile, n(z)~zkn(z)~zk. Numerical results based on the transfer matrix method, along with an average spectral analysis, were used to compute a certain range of thicknesses (with the optimal thickness of 235 nm) to obtain similar optical response (Tmax and Rmin). The average reflectivity spectrum of a PS-DM structure in the proposed optimal range was experimentally measured to be 1.3% from 300 to 1100 nm. Such structures can be used to enhance the efficiency of silicon solar cells and optoelectronic devices.