NOVELTY - An amorphous layer (A) having two or more metallic elements (M1,M2) or semiconductor (S1,S2) in large amount, and oxygen, dielectric material layer having semiconductor (S1) or metallic element (M1), and oxygen, and amorphous layer (B) having semiconductor (S1) or metallic element (M1), are laminated to obtain a laminate (10). Laminate is heat-processed, matrix (22) is formed with semiconductor (S1) or metallic element (M1), and quantum dot (24) of crystalline structure having mixed crystal of semiconductor and metallic elements is formed in matrix to form quantum dot structure (20).    USE - Manufacture of quantum dot structure for wavelength converter used for photoelectric conversion apparatus (all claimed) e.g. PN junction type solar cell.    ADVANTAGE - The quantum dot structure is manufactured with reduced defects and high quality. Since quantum dot is distributed three-dimensionally uniformly and with high density, the quantum dot structure having 3-dimensional periodicity and uniform distribution is obtained with high density. The decline in light-to-light conversion efficiency by temporary deterioration and decline in photoelectric conversion efficiency are suppressed.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) wavelength converter, which has the quantum dot structure. The quantum dot consists of a wavelength conversion composition which carries out wavelength conversion to light of energy lower than absorbed light with respect to specific wavelength range of absorbed light, and interval with particles which adjoin the quantum dot and have particle size less than the particle size of quantum dot; and    (2) photoelectric conversion apparatus, which has the wavelength converter arranged at the incident light side of photoelectric conversion layer. The effective refractive index of the wavelength converter is an intermediate refractive index of refractive index of the photoelectric conversion layer and refractive index of air.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view illustrating manufacture of quantum dot structure.    Laminate (10)    Substrate (12)    Silicon dioxide layer (14)    Silicon germanium oxide layer (16)    Silicon oxide layer (18)    Quantum dot structure (20)    Matrix (22)    Quantum dot (24)