Intrinsic and extrinsic origins of low-frequency noise in GaAs/AlGaAs Schottky-gated nanostructures

We study low-frequency noise in current passing through quantum point contacts fabricated from several GaAs/AlGaAs heterostructures with different layer structures and fabrication processes. In contrast to previous reports, there is no gate-dependent random telegraph noise (RTN) originating from tunneling through a Schottky barrier in devices fabricated using the standard low-damage process. Gate-dependent RTN appears only in devices fabricated with a high-damage process that induces charge trap sites. We show that the insertion of AlAs/GaAs superlattices in the AlGaAs barrier helps to suppress trap formation. Our results enable the fabrication of damage-resistant and thus low-noise devices.