Atomistic prediction on the configuration- and temperature-dependent dielectric constant of Be_0.25Mg_0.75O superlattice as a high-κdielectric layer

Abstract

Through DFT calculations, a Be0.25Mg0.75O superlattice having long apical Be–O bond length is proposed to have a high bandgap (>7.3 eV) and high dielectric constant (∼18) at room temperature and above.

Improving the water-resistance of MgO-based metal–insulator–metal capacitors by inserting a BeO thin film grown via atomic layer deposition

“…A recent ab initio calculation also supported this result, which indicated that maintaining a large bandgap value of >8 eV was possible. 34 Therefore, it could be anticipated that stacking the MgO and BeO layers was a feasible method to improve the electrical performances of the two constituting films while improving the electronic device stability over water-induced degradation. Nevertheless, as the Be compound is carcinogenic, it should be properly handled with adequate precaution.…”

On the atomistic origin of the polymorphism and the dielectric physical properties of beryllium oxide

“…The reason for that is that the “overbinding” LDA (prior research) relates to an artificially “strained” structure if compared to the “underbinding” GGA (PBEsol in our case), so imaginary GGA frequencies turn into positive LDA frequencies. Since the dielectric constant goes with the inverted squared frequencies, the numerical differences are rather large, despite very similar electronic structures, well known and discussed before 3,5 …”

“…Since the dielectric constant goes with the inverted squared frequencies, the numerical differences are rather large, despite very similar electronic structures, well known and discussed before. 3,5 As soon as external tensile strain is applied; however, there is huge boost of dielectric permittivity, particularly at low temperature, arising from the softening of the TO mode as shown in Figure 3 D. The strain sensitivity also indicates that it is possible to engineer dielectric permittivity through epitaxial strain.…”

“…As a result, the beryllium coordination resembles a tetrahedral motif, likewise accompanied by a significant decrease in the also LDA-based dielectric constant. 5 In what follows, we are trying to model and eventually explain the differing chemical behaviors of Be and Mg, in addition to finding the chemical reason for their difference in physical properties.…”

“…Nonetheless, more recent theoretical calculations showed the existence of a modified rock‐salt structure, making the beryllium atoms approach neighboring oxygen atoms, possibly due to their smaller size compared to magnesium. As a result, the beryllium coordination resembles a tetrahedral motif, likewise accompanied by a significant decrease in the also LDA‐based dielectric constant 5 . In what follows, we are trying to model and eventually explain the differing chemical behaviors of Be and Mg, in addition to finding the chemical reason for their difference in physical properties.…”