Avalanche photodetector and preparation method therefor

Abstract

The present disclosure provides an avalanche photodetector and a preparation method therefor. The avalanche photodetector comprises: a substrate, the surface of which comprises a first semiconductor layer; and a second semiconductor layer located on the substrate, wherein the first semiconductor layer comprises a first P-type doped region, a second P-type doped region, a third N-type doped region, a first intrinsic region, a third P-type doped region, a second intrinsic region, a second N-type doped region and a first N-type doped region which are sequentially arranged in a first direction, the dopant concentrations of the first to third P-type doped regions are sequentially decreased, the dopant concentrations of the first to third N-type doped regions are sequentially decreased, and the first direction is an electron flow direction; the second semiconductor layer sequentially covers part of the second P-type doped region, the third N-type doped region, the first intrinsic region and the third P-type doped region in the first direction; the first N-type doped region is connected to a first electrode; the third P-type doped region is connected to a second electrode; and the first N-type doped region is connected to a third electrode.