Structural and dielectric properties of crystalline and amorphous ZrO2

Intrinsic electron traps in atomic-layer deposited HfO2 insulators

“…On the other hand, 72% of oxygen atoms are bonded to 3 Hf atoms, 22% to 4, and 6% are bonded to 2 Hf atoms. These results are in good agreement with those of other theoretical studies 29,30 and, importantly, do not depend significantly on the force-field used. The oxide bandgap width is close to 6 eV, to be compared to the 5.9 eV experimental values for a-HfO 2 31 or a-HfAlO x .…”

Structural and dielectric properties of amorphousZrO2andHfO2

“…This issue was explored in our previous papers 3, 4 and we found that among the initial guesses, a density between 4.86 g/cm 3 and 5.32 g/cm 3 generates a robust amorphous structure for ZrO 2 . 12…”

“…6 The flowchart of our implementation of the ART method can be found in Ref. 4. As reported there, we found that, starting from a 96-atom supercell made from the perfect cubic fluorite crystal structure, a number of Monte-Carlo (MC) trials equal to 5 times the number of atoms (i.e., ∼ 500) was sufficient to produce a good amorphous structure.…”

“…In earlier work, 3 we generated models of a-ZrO 2 using an ab-initio molecular dynamics approach in a plane-wave pseudopotential framework, and studied their structural and dielectric properties. In a subsequent publication, 4 we described an alternate and more efficient method of generating amorphous structures based on the activation-relaxation technique (ART) of Barkema and Mousseau, 5 and presented a few preliminary results on amorphous ZrO 2 obtained using this approach. These calculations were carried out using a local-orbital basis approach embodied in the SIESTA code package.…”

Investigation of anomalous capacitance-voltage behavior caused by interface dipoles and the effect of post-metal-annealing

“…Therefore, a number of high-k materials, HfO 2 , ZrO 2 , Y 2 O 3 and their silicates, have been widely researched [4,5]. Among various high-k candidates, ZrO 2 has attracted a great amount of attention due to its relatively large dielectric constant (k~25) and relatively wide band gap (~5.0 eV) [6,7].However, the significant concentrations of defects in high-k dielectrics have been proved to result in the instability of devices, such as flat-band voltage shift. In order to characterize these defects comprehensively, a number of techniques have been proposed to investigate the reliability, degradation, device lifetime, defect loss, electron trapping and de-trapping, interface states etc.…”