Noise spectroscopy studies of GaAs/AlGaAs hall devices for optimizing micro- and nano-scale magnetic measurements

We report on a comprehensive characterization of the fluctuation properties of micro-Hall magnetometers based on a two-dimensional electron system (2DES) in δ-doped GaAs/AlGaAs semiconductor heterostructures. The analysis of the temperature- and frequency-dependent noise in a simple model of non-exponential kinetics reveals a distribution of activation energies for the 1/f ^α-type fluctuations. In addition to the 1/f-noise, two-level fluctuators with distinct energies are observed. We identify deep donor levels in AlGaAs (DX centers) as the predominant source of 1/f-noise and discuss the effect of the corresponding energy signature of these defect levels on the device performance in different temperature regimes, where we find an extremely low noise level at temperatures below ~ 100 K and above ~ 200 K.