Optoelectronic synaptic device including quantum dot(QD)-transition metal chalcogenide(TMD) heterojunction

A method of manufacturing an optoelectronic synaptic device, the method comprising:

• combining a two-dimensional semiconductor material on a silicon oxide substrate;
• forming a two-dimensional semiconductor material layer by wet-transferring the two-dimensional semiconductor material on another semiconductor substrate;
• forming an electrode layer by depositing a plurality of metal layers arranged to be spaced apart from each other on a portion of the two-dimensional semiconductor material layer;
• and
• forming a photoactive layer by applying an inorganic quantum dot colloidal solution and a ligand solution to some other surfaces on the two-dimensional semiconductor material layer and coating and drying the solutions,
• wherein a heterojunction is formed by directly contacting the inorganic quantum dots and the two-dimensional semiconductor material layer each other,
• wherein the ligand solution is a mixed solution in which an organic ligand and an organic solvent are mixed, and the organic ligand solution has a short carbon chain or ring of C1 to C8, and includes any one or more functional groups selected from a thiol group, an amine group, a carboxyl group, and a combination thereof,
• wherein the two-dimensional semiconductor material is a multilayer of two or more layers having a thickness of 50 to 70 nm,
• wherein the inorganic quantum dots include InAs having a bandgap of 1.2 eV or lower, the inorganic quantum dots being capable of sensing near-infrared light within a wavelength range of 800 to 1500 nm at 0.5 to 5 mW, and
• wherein a responsivity and a detectivity of the optoelectronic synaptic device increase, when a light intensity of the near-infrared light irradiated on the optoelectronic synaptic device decreases.