Generation‐recombination processes in AlGaN/GaN metal‐oxide‐semiconductor heterostructure field‐effect transistors (MOSHFETs) with HfAlO gate dielectric has been investigated through low‐frequency phase‐noise. Some devices tested exhibited noise spectra deviating from the well‐known (1/fγ)spectrum. These devices showed broad peaks attributed to generation‐recombination (GR) in the noise‐spectral‐density vs. frequency plots, which shifted toward higher frequencies at elevated temperatures. The unannealed and annealed MOSHFETs exhibited trap energy values as 0.22 eV and 0.11 eV at drain bias values of 6.3 V and 10 V, respectively. We also monitored the effect of source‐drain bias on the excess GR noise. The time constant of the traps decreased from 16.7 ms to 2.1 ms as we increased the VDS from 10 V to 18 V for the annealed devices. This effect can be explained by the potential barrier lowering (Frenkel‐Poole effect) of the traps by electric field (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)