Low-frequency noise in AlInAs/InGaAs/InP MBE- and MOCVD-grown HFETs

We report on the low-frequency noise (LFN) of InP HFETs based on MOCVD- and MBE-grown materials. The spectral density of the drain current fluctuations was found to be close to 1/ f with no dominating superimposed generation-recombination component. In order to avoid a non-uniform electron distribution under the gate, the measurements were performed in the linear regime, i.e., the drain to source bias was kept at 0.1 V. It was assumed that the LFN stems from the carrier number fluctuations. A good fit of the measured and simulated drain current fluctuations, plotted versus the drain current, supports this assumption. An effective density of traps was extracted which reflects the contribution to the noise from both the contact resistances and the density of bulk and interface traps.