Material Dependence of Metal Grating on SOI Photodiode for Enhanced Quantum Efficiency

Material dependence of line-and-space metal grating among gold, silver, and aluminum, is experimentally investigated for a 100-nm-thick silicon-on-insulator p-n junction photodiode in terms of enhanced light sensitivity. It is found that light sensitivity in the visible long-wavelength region is enhanced with any grating material, and the peak wavelengths, which are determined by the grating period, are not much affected by the material. The relationship between the peak wavelength and the grating period is explained theoretically. The results indicate that the grating material can be selected from these materials by taking into account the short-wavelength sensitivity and compatibility with applications.