Fig. 3: Optimization of multi-layered PCM for the super-resolution near-field effect.

a I. Schematic of multi-layered PCM for the super-resolution near-field effect. II. TEM image of the optimized and deposited multi-layered PCM, in which the PCM and dielectric layers were composed of Sb₆₅Se₃₅ and ZnS-SiO₂. The upper dielectric layer was 183.15 nm thick, the first PCM layer was 21.64 nm thick, the medium dielectric layer was 4.41 nm thick, the second PCM layer was 11.54 nm thick, and the bottom dielectric layer was 4.75 thick. b I. Schematic of multi-layered PCM and aperture formation on the 1st PCM layer. II. Contour plots of aperture size on the first PCM layer according to the thickness of the upper dielectric layer (140–200 nm) and the medium dielectric layer (5–15 nm) for varying first and second phase-change layer thicknesses (1) 10–20 nm, (2) 10–15 nm, (3) 10–10 nm, (4) 15–20 nm, (5) 15–15 nm, (6) 15–10 nm, (7) 20–20 nm, (8) 20–15 nm, and (9) 20–10 nm. II. Contour plots of the aperture size on the first PCM layer with optimized PCM layer thicknesses of 20–10 nm (I–9) (other plots are available in Supplementary Information I-[1–8].) III. Figure S2(a)) IV. Temperature profile on the first PCM layer and aperture-prediction results. c I. Schematic of multi-layered PCM and aperture formation on the second PCM layer. II. Contour plots of the aperture size on the second PCM layer according to the thicknesses of the upper (140–200 nm) and medium dielectric layers (5–15 nm) and first and second PCM layers: (1) 10–20 nm, (2) 10–15 nm, (3) 10–10 nm, (4) 15–20 nm, (5) 15–15 nm, (6) 15–10 nm, (7) 20–20 nm, (8) 20–15 nm, and (9) 20–10 nm III. Contour plots of the aperture size on the second PCM layer with optimized thicknesses of 20–10 nm (II-9) (other plots are available in Supplementary Information II-[1–8].) IV. Temperature profile of the second PCM layer and aperture-prediction results