Crystal Structures

Computational study of structural and elastic properties of random AlxGayIn1 −x−yN alloys

“…Then we also used the VFF model to examine the elastic constants, concluding that the composition dependence of c i j exhibits a deviation from Vegard-like model in the form of sublinear bowing. This is in accordance with suggestions already made in the literature [46,49]. We also presented accurate quadratic function fits, which very well approximate the dependence of c i j on composition, including aforementioned bowing effect.…”

“…To summarize this section, we have shown that the Keating VFF model predicts a quadratic dependence of the elastic constants c i j on Al x Ga y In 1−x−y N alloy composition. This effect is in agreement with the previous literature studies [46,49]. We believe that, even though the effect is not very large, the awareness of it could improve description and modelling of devices based on low dimensional nitride structures, such as quantum dots and quantum wells.…”

“…The literature indicates that bowing in the alloy elastic constants c i j should indeed be expected. Chen and Sher in their book [46] point out that the value of c i j should be always negative, which is the case in our studies. They argue that since the elastic properties of semiconductors correlate with the inverse power of the lattice constant and that lattice constants for alloys follow Vegard's law, then the c i j dependence on composition should be sublinear.…”

“…The dependence of bond lengths on concentration is usually also linear, however, bond lengths remain much closer to their original bond length in bulk binary material, rather than to the average bond length predicted by a Vegard-like law (see e.g. [45,46]). This linear dependence of the bond lengths in the alloy on the concentration of Al and Ga cations, x and y respectively, can be described by the linear form…”