Electron trapping in ferroelectric HfZrO4 and Al- and Si-doped layers

•We revealed trap energies and densities in FE and non-FE HfO2 and HfZrO4 layers.•The high deep trap density (~1019 cm−3) poses challenges for electrostatic control.•The observed traps are likely intrinsic to hafnia/zirconia lattice (polarons). Electron trapping in ferroelectric and non-ferroelectric HfO2-based layers was studied at room temperature by charge injection and photodepopulation techniques. The comparison of inferred energy distribution and density of trapped electrons in differently processed samples shows insignificant impact of Al- and Si-doping on trapping properties suggesting intrinsic nature of the observed traps. A comparison to the HfZrO4 layers is provided. The volume concentration of deep traps, most of which are energetically distributed between 2 and 3.5 eV below the HfO2 conduction band, is found to be in the range of 1019 cm−3.