Effect of Metal Contact on Silicon 2D-Gratings Light Absorption

In this paper we describe our study results in metal contact effect on light absorption in a 2D Silicon grating structure. Light power absorption is calculated using FDTD method and we found that by adjusting metal material and the grating width, we can tune light absorption in 850 nm wavelength. By using gold metal contacts, we could achieve 0.21 peak absorption compared to 0.069 peak absorption in bulk Silicon. The calculation also shows that most of the light in NIR spectrum is absorbed by the metal contacts, rising a possibility of using IPE method to further increase the devise photoresponsivity.