Detector material and preparation method thereof

Provided is a preparation method of a detector material. The present disclosure epitaxially grows a buffer layer on a surface of a gallium arsenide substrate, deposits a silicon dioxide layer on the buffer layer, and etches the silicon dioxide layer on the buffer layer according to a strip pattern by photolithography and etching to form strip growth regions with continuous changes in width. Finally, a molecular beam epitaxy (MBE) technology is used to epitaxially grow the detector material in the strip growth regions under set epitaxy growth conditions. Because of the same mobility of atoms arriving at the surface of the substrate, numbers of atoms migrating to the strip growth regions are different due to different widths of the strip growth regions, such that compositions of the material change with the widths of the strip growth regions or a layer thickness changes with the widths of the strip growth regions.