Relaxation mechanisms in 2D electron gas and origin of 1/f noise in HEMT´s

Experiments aiming at finding the microscopic origin of 1/f noise in HEMT´s are described. They were suggested by the existence of some specific energy relaxation mechanisms in a 2DEG. 1/f-like noise has been found in the drain voltage of lattice-matched InAlAs/InGaAs HEMT´s, at drain voltages(V_DS) lower than 55 mV and applied gate voltage V_GS=OV. The tendency for the drain voltage noise spectral density (S_v) is to follow a V²_DS dependence, but local deviations manifest at some given voltages. These voltages seemed to be in a good correspondence with some specific phonon energies in the InAlAs/InGaAs system. These phonon signatures indicate that 1/f noise in the channel of InAlAs/InGaAs HEMT´s is brought about by lattice scattering. A mobility fluctuation 1/f noise parameter(α) of about 10^-3 for the whole channel has been estimated. It stands for an indirect proof of lattice participation into the channel 1/f noise