Decomposition of 1/f Noise in Al_xGa_1-xAs/GaAs Hall Devices

We present a systematic study of the low-frequency noise in micron and submicron Hall devices made from Al_xGa_1-xAs/GaAs heterostructures. In a sample with feature size as small as 0.45  μm we observe a nonmonotonic temperature dependence of the noise power spectral densities (PSD’s) at temperatures where surface states and deep-level excitations are frozen out. Near the temperature where the noise peaks, the PSD’s can be described by a thermally activated two-level random telegraph signal, i.e., the 1/f noise originating from switching events in the highly doped Al_xGa_1-xAs layer is resolved into a single Lorentzian spectrum.