Correlation between flicker noise and current linearity in ferromagnetic-GaAs-metal tunnel contacts

The low frequency noise behavior of the in-plane current through ferromagnetic tunnel contacts on a III-V semiconductor is evaluated. Measurements are performed between ferromagnetic and ohmic contacts and between the two ferromagnetic contacts which have different coercive fields in a lateral [Ta/IrMn/CoFe]/AIOx/GaAs/AIOx/[CoFe/NiFe/Ta] structure. The resistance and current noise spectral density of the CoFe/NiFe/Ta contact are higher than that of Ta/IrMn/CoFe. Strong generation-recombination noise is found in high resistivity devices. It is assumed that the deep level traps are due to DX centers in the AlGaAs layer, possibly resulting from the diffusion of Ni into the semiconductor.