Light Absorption Improvement of Si Photodetector with 2D Grating Structure at Near-infrared Wavelength Range

A Si photodetector with 2D grating structure is geometrically optimized to improve the absorption of light at near-infrared (NIR) wavelength range. The cell's width is 600 nm, with pillar and substrate thickness of 500 nm each. The periodic characteristic of light absorption allows the altering of the device's absorption spectrum by pillar width variation. The depletion region area is configured to allow optimum photogenerated current. Absorption peak of 0.17 is obtained at 370 nm pillar width, a ~146% improvement from the bulk absorption at 0.069, with cell responsivity reaching 17.7 nA/µm/W.