The electrostatic barrier of a Au/1.4 nm HfO2/0.8nm SiO2/Si(001) structure was mapped with ballistic hole emission microscopy on p-type silicon substrates to nanoscale dimensions over a square micrometer. The 1.4 nm HfO2 layer showed three concentrations of barrier heights localized in different regions of the sample. These concentrations are consistent with the barrier heights of HfO2/Si-p, native SiO2/Si-p, and one centered at −0.45eV. The latter barrier height is attributed to an ultrathin HfO2 (1–3 monolayers). This study demonstrates the power of electrostatic barrier mapping to visualize complex and nonuniform interfaces.
A low cost rotatable holder is designed and fabricated for the Quantum Design VersaLab that enables rotation of the device over 90° without the need for rewiring. This allows the magnetic field to be oriented from in plane to perpendicular to plane for the devices, enabling angle dependent measurements. Several measurements are performed to test performance against the standard sample mounting puck that comes with the system. In addition, anomalous Hall measurements are performed on Si|SiO2|Ta (5 nm)|CoFeB (1 nm)|MgO (1.6 nm)|Ta (Cap) devices with the field perpendicular and parallel to the plane of the sample to demonstrate rotation.
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