Terahertz detection by AlGaN/GaN HEMTs at high intensity

We report on the photoresponse of AlGaN/GaN HEMT to THz radiation of low and high intensity. We show that the response vs. gate bias dependence can be described by the theory of Dyakonov-Shur in the whole range of radiation intensity. Unusual behavior of the photoresponse vs. intensity was observed under laser irradiation: a quadratic increase of the response followed by saturation. We speculate that this phenomenon can be explained by hot electrons capture by traps in AlGaN or buffer layers.