AmorphousHfO2andHf1−xSix

Structure and dielectric properties of amorphous high-κoxides: HfO2, ZrO2, and their alloys

“…2a we note that the threecoordinated O atoms and six-coordinated Hf atoms dominate the a-HfO 2 structures which agree with the known ab initio results. 7,16 From Fig. 2b we find that the first peaks in the Hf-O, O-O and Hf-Hf RDFs are at 2.1Å, 2.8Å, and 3.6Å, respectively, again compare well with ab inito studies.…”

“…2b we find that the first peaks in the Hf-O, O-O and Hf-Hf RDFs are at 2.1Å, 2.8Å, and 3.6Å, respectively, again compare well with ab inito studies. 7,20 These comparisons indicates that the classical MD can reliably generate amorphous structures of the metal oxides. Importantly, the efficiency of classical MD allows us to generate ensembles of amorphous samples of Hf 1−x Zr x O 2 for each given concentration x, which is essential for statistical analysis of the dielectric properties (see below).…”

“…1 Several promising candidates are metal oxides such as HfO 2 , 2,3 ZrO 2 3-5 and Al 2 O 3 , 6 all of which have high value of dielectric constant κ. High-κ metal oxides in their amorphous (a-) form are more preferable as a gate oxide over their crystalline form due to several important advantages they provide: (i) isotropic physical properties; (ii) no crystalline domain boundary which leads to less defects at the interface with the Si substrate; and (iii) good compatibility with the conventional CMOS fabrication process. Some alloy structures of these high-κ metal oxides are also being studied extensively [7][8][9][10][11][12] and, in fact, a Hf based alloy material has already been in its third generation of production as a gate oxide in the semiconductor industry and further improvements of thermal stability, dielectric constant and material preparations are underway. [8][9][10] In clear contrary to the abundance of experimental results in the literature, theoretical studies of the structure and dielectric properties of amorphous metal oxides and their alloys are quite limited.…”

“…Both MD and KMC are useful for the simulation of the initial atomic layer deposition processes of the amorphous film growth. To generate bulk amorphous structures, ab inito MD simulations can be used in a melt and quench scheme, a-HfO 2 , 3,7,16 a-ZrO 2 3,5,17 and their silicates 7,12 have been successfully simulated this way. The activation-relation technique is another method to generate structures of continuous disordered systems 18 and has been applied to generate a-ZrO 2 structures.…”

First-Principles Investigations on Structural, Elastic, Electronic, and Optical Properties of Tetragonal HfSiO4

“…Its fundamental properties, e.g., electrical, optical, compositional, and structural properties have been analyzed, which indicates that hafnium silicate can be considered as one of the promising candidates for high-k gate dielectric applications. Moreover, theoretically, there are some calculations of hafnium silicate including the generalized gradient approximation (GGA) with CASTEP code [28], the gradient-corrected PW91 functional with VASP code [29], the diagonalization method [30], the perturbation formulae with the crystal-field theory [31], the ab initio molecular dynamics simulations [32], the LDA with ABINIT code [33], and the spin-polarized GGA with VASP code [34]. The energy levels of the various charge states of the oxygen vacancy and the oxygen interstitial in crystalline HfSiO 4 [28]; thermal decomposition mechanisms of hafnium silicates [29]; structural, vibrational, and dielectric properties of HfSiO 4 [33], etc.…”