Visualizing metal/HfO2/SiO2/Si(001) interface electrostatic barrier heights with ballistic hole emission microscopy

The electrostatic barrier of a Au/1.4 nm HfO 2 / 0.8 nm SiO 2 / 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 HfO 2 layer showed three concentrations of barrier heights localized in different regions of the sample. These concentrations are consistent with the barrier heights of HfO 2 / Si-p, native SiO 2 / Si-p, and one centered at − 0.45 eV. The latter barrier height is attributed to an ultrathin HfO 2 (1–3 monolayers). This study demonstrates the power of electrostatic barrier mapping to visualize complex and nonuniform interfaces.The electrostatic barrier of a Au/1.4 nm HfO 2 / 0.8 nm SiO 2 / 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 HfO 2 layer showed three concentrations of barrier heights localized in different regions of the sample. These concentrations are consistent with the barrier heights of HfO 2 / Si-p, native SiO 2 / Si-p, and one centered at − 0.45 eV. The latter barrier height is attributed to an ultrathin HfO 2 (1–3 monolayers). This study demonstrates the power of electrostatic barrier mapping to visualize complex and nonuniform interfaces.