光照面积对MSM型氮化镓光电二极管超快时间响应的影响

We investigate the influence of spatial illumination profiles on the temporal response of metal–semiconductor–metal (MSM) gallium nitride (GaN) photodiodes. Using both simulation and experimental measurements, we compare the response curves under two scenarios: illumination confined to the active area between electrodes and extended illumination beyond the contacts. The results show that limiting the beam illumination to the active region significantly sharpens the response, reducing the long decay tails associated with slow carrier drift from peripheral regions. The experimental data closely match simulation predictions, confirming that illumination geometry plays a critical role in optimizing photodiode performance for ultrafast detection applications.