A capacitor includes a lower electrode, a dielectric structure over the lower electrode, the dielectric structure including at least one crystallized zirconium oxide (ZrO2) layer and at least one amorphous aluminum oxide (Al2O3) layer, and an upper electrode formed over the dielectric structure. A method for fabricating a capacitor includes forming a lower electrode over a certain structure, forming a dielectric structure including at least one crystallized zirconium oxide (ZrO2) layer and at least one amorphous aluminum oxide (Al2O3) layer over the lower electrode, and forming an upper electrode over the dielectric structure.