One-dimensional antireflection gratings in (100) silicon: a numerical study

The antireflection properties of V-grooved gratings in (100)crystalline silicon are studied numerically by use of rigorouselectromagnetic theory. This study shows that these gratings canexhibit antireflective behavior only for TM-polarizedradiation. The V-grooved structures are analyzed as a function ofgrating period, duty cycle, and depth of a SiO(2) mask layerthat is added to the tops of the V-grooved mesas. Specificantireflection grating designs (the duty cycle and depth versus theperiod) are presented that illustrate TM-polarized reflectivity muchless than 10(-3) with periods as high as 80% the wavelengthof incident radiation. These designs exhibit good tolerance tofabrication errors and grating's plane deviations in aplanar-diffraction mounting.