Broadband Antireflection Coatings Made of Resonant Submicron- and Micron-Sized SiGe Particles Grown on Si Substrates

The solid-state dewetting phenomenon was used to obtain submicron- and micron-sized SiGe particle arrays by the Ge deposition on Si(100) substrates. Their transmission and reflection spectra were measured and numerically modeled by the FDTD method. They exhibit resonance effects in broad infrared spectral ranges, depending on the particle size. The broadband antireflection property is associated with wide particle size distributions and the influence of a high-index substrate. The results show that the dewetting phenomenon provides the natural formation of arrays of particles shaped as close to a sphere segment, and they turned out to be effective as antireflection coatings.