Photoelectric detector structure and forming method thereof

The invention provides a photoelectric detector structure and a forming method thereof, and the structure comprises a silicon-on-insulator substrate, the silicon-on-insulator substrate comprises top silicon, the top silicon comprises a growth region and doped regions located at the two sides of the growth region, and a dielectric layer is formed on the surface of the top silicon; an epitaxial layer is formed in the dielectric layer of the growth region, the width of the epitaxial layer in the growth region is equal to that of the growth region, the epitaxial layer extends into the top silicon, and the surface of the epitaxial layer is higher than that of the dielectric layer; and a protective layer is formed on the side wall of the epitaxial layer in the dielectric layer. According to the photoelectric detector structure and the forming method thereof provided by the invention, the protective layer is used for protecting the dielectric layer from being transversely etched, and the collimation of the epitaxial