LF EXCESS NOISE-ANALYSIS 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 inf luence: Al mole-fraction in the n-AlGaAs layer, type of the buffer lay er (p- or n- doped GaAs or AlGaAs), In molefraction in pseudomorphic s tructures. From the LF drain noise behaviour versus gate and drain bia ses and temperature (90K to 300K), pseudomorphic devices are found to present lower drain current noise and less G-R contributions when comp ared to conventional HEMTs. This difference might result from a lower deep level concentration.