Remarks of an Extensive Investigation on the Microwave HEMT Behavior Under Illumination

This letter presents valuable remarks based on an extensive experimental study of the microwave behavior for a GaAs HEMT under CW infrared and visible laser exposure. The comparison of both dc and microwave (scattering and noise) parameters with and without illumination has highlighted that the device behavior is significantly affected by the light exposure. The observed optical effects can be ascribed to the threshold voltage shift originating from the internal photovoltaic effect. The light sensitivity has shown to be more pronounced at shorter wavelength.