Fig. 1. Two-dimensional structure of double-diffused positive-illumination InGaAs/InP SAGCM：（a） Structure after deep diffusion is complete； （b） Structure after shallow diffusion is complete

Fig. 2. The simulation of diffusion profile：（a） Contour after shallow diffusion； （b） Contour after deep diffusion

Fig. 3. Distribution of Zn impurity concentration in InP

Fig. 4. Fitting curves for X_j3 and X_j4

Fig. 5. Diffusion depth characterization results：（a） SEM test results； （b） SIMS test results

Fig. 6. Fitting results of deep diffusion depth from SEM and SIMS tests

Fig. 7. Variation of electric field with different MW

Fig. 8. Variation of breakdown voltage and punch-through voltage with different MW

Fig. 9. Simulation and test results：（a） Comparison of dark current （IV） Simulated and measured curves； （b） Photodetector characteristics curve from IV tests

Fig. 10. Relationship between multiplication width （MW） and breakdown voltage （V_BR）

Fig. 11. Trends in Dark Count Rate （DCR） variation with temperature and MW