Fig. 1. Analysis and optimization of influence of nano-LED shape. (a) Structure diagram of cylindrical gallium nitride-based nano-LED; (b) simulation model diagram of COMOSL; (c) schematic diagram of quantum well structure; (d), (e), (f) Two-dimensional (2D) cross-sectional electric field distribution diagrams of cylindrical nano-LED at D=0, 400, and 500 nm; (g), (h), (i) far-field polar coordinate diagrams of cylindrical nano-LED at D=0, 400, and 500 nm; (j) relationship between top diameter of cylindrical nano-LED and far-field intensity; (k) relationship between top diameter of cylindrical nano-LED and vertical emission angle

Fig. 2. Analysis and optimization of influence of gallium nitride thickness in cylindrical nano-LED quantum wells. (a) Quantum well structure; (b), (c), (d) 2D cross-sectional electric field distribution diagrams of cylindrical nano-LED at T=3,5, and 7 nm; (e) changes in far-field radiation intensity under different T; (f) changes in far-field intensity with emission angle at T=3, 5, and 9 nm; (g) relationship between quantum well thickness, overall emission angle, and far-field intensity

Fig. 3. Analysis and optimization of influence of width of external dielectric layer of cylindrical nano-LED. (a) Schematic diagram of cylindrical nano-LED structure after adding external dielectric layer; (b), (c), (d) 2D cross-sectional electric field distribution diagrams of cylindrical nano-LED at W=50, 100, and 200 nm; (e) changes in far-field radiation intensity under different W; (f) far field intensity changes with emission angle at W=50, 200, and 300 nm; (g) far field intensity changes with emission angle locally at W=50, 200, and 300 nm; (h) relationship between width of external dielectric layer and far field intensity; (i) relationship between width of external dielectric layer and overall emission angle

Fig. 4. Analysis and optimization of influence of refractive index of external dielectric layer of cylindrical nano-LED. (a) 2D cross-sectional electric field distribution diagram of cylindrical nano-LED at W=200 nm and n=1.5; (b) changes in far-field radiation intensity under different n; (c) relationship between refractive index of external dielectric layer and far-field intensity; (d) relationship between refractive index of external dielectric layer and overall emission angle; (e) 2D cross-sectional electric field distribution diagram of cylindrical nano-LED at W=300 nm and n=1.5; (f) changes in far-field radiation intensity under different n; (g) relationship between refractive index of external dielectric layer and far-field intensity; (h) relationship between refractive index of external dielectric layer and overall emission angle

Fig. 5. Final optimization effect comparison. (a) 2D cross-sectional electric field distribution diagrams of cylindrical nano-LED before and after optimization; (b) far-field radiation polar coordinate diagrams of cylindrical nano-LED before and after optimization