Fig. 1. Schematic structure of (a) standard AlGaN SAM APD with bevel angle and FP termination, and (b) standard AlGaN SAM APD with triple-mesa and FP termination.

Fig. 2. (a) I–V characteristics in dark and under illumination and gain for AlGaN SAM APD with different bevel angles and FP structure, (b) schematic structure of AlGaN SAM APD without FP, and (c) I–V characteristics in dark and under illumination as well as gain for AlGaN SAM APD without FP.

Fig. 3. Simulated two-dimensional electric field distribution for APD with bevel angle of (a) 10°, (b) 20°, (c) 40°, and (d) 60°, and electric field distribution along x direction in multiplication layer at (e) y = 190 nm, (f) y = 280 nm, (g) y = 350 nm with reverse bias 30 V.

Fig. 4. (a) Two-dimensional electric field for AlGaN APD with 60° bevel angle and FP structure at reverse bias of 30 V, (b) electric field distribution along x direction in multiplication layer for 60° bevelled AlGaN APD with and without FP structure.

Fig. 5. I–V characteristic curves in dark and under illunination and gain for AlGaN APDs with different mesa sizes (a) with and (b) without FP. (c) Schematic structure of AlGaN APD with triple-mesa structure.

Fig. 6. Two-dimensional electric field distribution at reverse bias of 30 V for APD with first-mesa size (a) 5.2 μm, (b) 4 μm, and (c) 1.6 μm.

Fig. 7. Two-dimensional electric field distribution at reverse bias of 30 V for the APD with FP and first-mesa size (a) 5.2 μm, (b) 4 μm, (c) 1.6 μm, and (d) ideal structure.