Fig. 1. P-I-N type GaN ultraviolet diodes. (a) Schematic cross-sectional structure; (b) cathodoluminescence mapping image of GaN wafer used; (c) top-viewed image of fabricated diodes

Fig. 2. Forward temperature-dependent I-V curves of P-I-N type GaN ultraviolet (UV) diodes

Fig. 3. Forward I-V characteristic and fitting curves at 300 K

Fig. 4. Dependence of n and E_g on temperature at forward high voltage

Fig. 5. (a) Forward electroluminesence (EL) curves; (b) schematic bandgap diagram of conductive dislocations of P-I-N type GaN UV diodes

Fig. 6. (a) Schematic diagram of defect-assisted tunneling process; (b) dependence of E₀ and n on temperature of P-I-N type GaN UV diodes

Fig. 7. Dependence of β₁ and β₂ on temperature for V_F<1.35 V