Multiphoton Absorption in Gallium Nitride and Silicon Carbide Photodiodes: Applications for Single-Event Effects Tests

We report on the investigation of multiphoton absorption processes in gallium nitride (GaN) and silicon carbide (SiC) photodiodes. Up to three-photon absorption mechanisms were evidenced on both materials because of a wavelength-tunable femtosecond laser chain. These results are applied to single-event effect (SEE) investigations on a commercial GaN high-electron mobility transistor (HEMT). We could trigger single-event transients (SETs) by focusing the beam throughout the silicon substrate and collect charge that was photogenerated in the GaN layer by a three-photon absorption process.