The invention discloses a
silicon-avalanche
photodetector (Si-APD) with
black silicon as a photosensitive layer and a preparation method of the Si-APD with the
black silicon as the photosensitive layer, and belongs to the field of photoelectric detection technology. The Si-APD comprises a
silicon intrinsic substrate 1, an N<+> region 2, a P type region 3, an annular N type region 4, an N<+> region
black silicon layer 5, a P<+> region 6, an upper
electrode 7 and a lower
electrode 8, wherein the N<+> region 2 is located in the middle of the upper surface of the
silicon intrinsic substrate 1, the P type region 3 is located below the N<+> region, the annular N type region 4 is located on the periphery of the upper surface of the silicon intrinsic substrate, the N<+> region black silicon layer 5 is located on the upper surface of the N<+> region, the P<+> region 6 is located on the lower surface of the silicon intrinsic substrate, the upper
electrode 7 is located on the upper surfaces of the N<+> region black silicon layer and the annular N type region, and the lower electrode 8 is located on the lower surface of the P<+> region. According to the Si-PAD, the black silicon material serves as the photosensitive layer, and meanwhile the annular N type region is additionally arranged on the peripheries of the N<+> region and the P type region. Thus, the Si-APD with the black silicon as the photosensitive layer can absorb light
waves of a near-
infrared band and have higher light absorptivity and a wider response
wave band, the preparation technique is simple, the cost is low, and the Si-PAD has the advantages of being easy to integrate, quick in response speed, high in
responsivity and wide in response
wave band.