The metal-semiconductor-metal (MSM) diodes are very attractive for short wavelength detection due to their simple structure, high-speed response and low dark current. In this work we present the results of fabrication of AlGaN MSM photodetectors on sapphire substrates. Two types of heterostructures are fabricated and analyzed. The detector's characteristics are studied for different Schottky barrier metals

A two-dimensional model is used to investigate the characteristics of the pulsed response and efficiency of metal—semiconductor—metal photodiode structures made of GaAs. The active area of these structures is 400 μm × 400 μm and the distance between the contacts is 10 μm. An increase in this distance ensures a sufficiently homogeneous distribution of the electric field in the active region of the photodiode. The capacitance of the interdigital system of contacts, based on the Schottky barrier, is considerably less than that of a pin photodetector of equal area and does not impose any restrictions on the characteristics of the pulsed photodiode response. The calculated response time of this photodiode structure (110 ps at half-amplitude) agrees with the experimental value.