The present disclosure provides a photo sensing device and a method of forming the same. The photo sensing device includes a substrate comprising a silicon layer at a front surface of the substrate; a photosensitive member extending into and at least partially surrounded by the silicon layer, and a composite layer disposed between the photosensitive member and the silicon layer and surrounding the photosensitive member. The silicon layer includes a first doped region adjacent to a first side of the photosensitive member and a second doped region adjacent to a second side of the photosensitive member opposite to the first side. The first doped region has a first conductivity type and includes a heavily doped region and a lightly doped region adjacent to the heavily doped region. The second doped region has a second conductivity type different from the first conductivity type.