NOVELTY - The method comprises dissolving a tertiary phosphine and/or a primary amine in a halogenated solvent for preparing a first solution, adding semiconductor nanocrystals to the first solution for inducing etching of the semiconductor nanocrystals, irradiating the first solution with exciding light such as UV excitation light having a wavelength able to be absorbed by the semiconductor nanocrystals for inducing etching of the semiconductor nanocrystals, and exposing the first solution including the semiconductor nanocrystals to oxygen for inducing etching of the semiconductor nanocrystals.    USE - The method is useful for etching semiconductor nanocrystals such as a heterostructure including a junction structure, a core-shell structure and a superlattice structure and comprising compositions (claimed), semiconductor nanocrystals are useful for biological labeling, LEDs, lasers, solar cells, and wireless communication.    ADVANTAGE - The method is capable of effectively etching semiconductor nanocrystals without any complicated steps thus precisely and controlling the properties absorption wavelength, emission wavelength, emission intensity, average size, size distribution, shape and surface state of semiconductor nanocrystals.    DETAILED DESCRIPTION - The method comprises dissolving a tertiary phosphine and/or a primary amine in a halogenated solvent for preparing a first solution, adding semiconductor nanocrystals to the first solution for inducing etching of the semiconductor nanocrystals, irradiating the first solution with exciding light such as UV excitation light having a wavelength able to be absorbed by the semiconductor nanocrystals for inducing etching of the semiconductor nanocrystals, and exposing the first solution including the semiconductor nanocrystals to oxygen for inducing etching of the semiconductor nanocrystals. The semiconductor nanocrystals comprise group of II-VI, III-V and IV-VI compound semiconductor nanocrystals. An etching rate of the semiconductor nanocrystals is controlled by a concentration of semiconductor nanocrystals, a concentration of the primary amine, a concentration of phosphine, a type of phosphine, a type of halogenated solvent, oxidizing conditions, a wavelength of the excitation light, and an irradiation power of the excitation light. The wavelength of the excitation light is shorter than an absorption edge of the semiconductor nanocrystals.    DESCRIPTION OF DRAWING(S) - The diagram shows a high resolution transmission electron microscopic view of an average size of zinc blend cadmium selenide-570 nanocrystals before and after etching.