Compared microwave performances of a high-speed PIN photodiode and a traveling fringes photodetector

We discuss the comparative performances of the high-speed top-illuminated photodiode geometry and of the traveling fringes photodetector geometry. This last one relies on the synchronous drift in a semiconductor of photogenerated carriers with a moving fringes pattern. Linearized rate equations are solved taking into account dielectric relaxation and space charge field effects in both geometries. Estimations of the maximum available microwave power are presented for GaAs, Si, SiC, and GaN. This comparison is based on quite idealistic materials in order to draw out inherent limitations of these two approaches.