A method may be used for manufacturing a semiconductor element. The method may include the following steps: preparing a substrate; forming a semiconductor layer on the substrate, wherein the semiconductor layer includes crystallized two-dimensional layers; forming a source electrode and a drain electrode on the semiconductor layer; forming an semiconductor member by wet etching the semiconductor layer using sodium hypochlorite as an etchant, wherein the wet etching results in a residue; and removing the residue using purified water and an inert gas.