Photodetection Element With Localized Schottky Junctions

The patent applies local quality by creating different junction types in different regions of the periodic concave/convex structure. Specifically, Schottky junctions are formed only in the concave portions where light absorption is enhanced, while convex portions have non-Schottky junctions (such as ohmic junctions or insulating layers). This localized differentiation allows the structure to maximize light absorption in concave regions without increasing dark current across the entire surface, as convex regions do not contribute to dark current generation.

The patent employs composite materials by combining silicon semiconductor layer with metal film layers to form a Schottky junction structure. This composite approach enables the detection of near-infrared light with wavelengths longer than the silicon band gap limit, achieving detection up to approximately 1700 nm. The metal-semiconductor composite structure maintains compatibility with standard silicon fabrication processes while extending the detection capability beyond what pure silicon PN junctions can achieve.

The patent applies segmentation by dividing the periodic concave/convex structure into functionally distinct regions: concave portions that form Schottky junctions for high sensitivity detection, and convex portions that form non-Schottky junctions to minimize dark current. This segmentation strategy maintains high detection sensitivity by concentrating Schottky junctions in light-absorbing concave regions while eliminating dark current sources from convex regions, thereby improving the signal-to-noise ratio without sacrificing sensitivity.