Patent attributes
A capacitor includes a first electrode, an insulating film and a second electrode. The insulating film includes n layers of barrier layers each consisting of a material having a bandgap larger than a first bandgap and having a relative permittivity smaller than a first relative permittivity, and (n−1) layers of well layers each consisting of a material having a bandgap smaller than the first bandgap and having a relative permittivity larger than the first relative permittivity. The barrier layers and the well layers are stacked by turns. Discrete energy levels are formed in each of the well layers by a quantum effect. Thicknesses of the n layers of the barrier layers are not smaller than 2.5 angstroms. A thickness dm (angstrom) and a relative permittivity εm of an m-th barrier layer satisfying the condition: 2.5 >(d1/ε1+d2/ε2+. . . +dn/εn).
