LF Excess Noise of AlGaAs/GaAs and AlGaAs/InGaAs/GaAs HEMTs

The quality of AlgaAs/GaAs/buffer layer on GaAs HEMTs and of AlGaAs/ In GaAs/GaAs HEMTs is studied on the basis of technological parameter influence: Al molefraction in the n-AlGaAs layer, type of the buffer layer (p- or n- doped GaAs or AlGaAs), In molefraction in pseudomorphic structures. From the LF drain noise behaviour versus gate and drain biases and temperature (90K to 300K), pseudomorphic devices are found to present lower drain curent noise and less G-R contributions when compared to conventional HEMTs. This difference might result from a lower deep level concentration