  We present a guide for the design and fabrication of a CMOS-compatible
metamaterial microstructure as an absorber of visible light with exceptionally
high absorption efficiency (~ 98%), for wavelengths 400nm-700nm. The structural
parameters of the microstructure have been optimized by using Finite Element
method (FEM) based COMSOL multyphysics software simulations. An optimized 2D
unit cell of the structure consists of 4um by 160 nm TiN base on glass
substrate covered with 70 nm thick silicon dioxide (SiO2). A periodic structure
of titanium nitride (TiN) straps (each of 90 nm thick and 2-micron wide) is
deposited over SiO2. The straps are capped with 40 nm thick layer of
high-temperature dielectric hafnium dioxide (HfO2) with periodicity of
4-micron. This unit is symmetric along the other dimension and repeated
periodically along the horizontal direction. Additionally, though this
microstructure was optimized for visible light spectrum, it also shows almost
similar absorption of ~96% intigrated over wavelenght spectrum from 400 nm to
1200 nm. This investigation shows good agreement between simulation and
experimental results.
