Limits...
Topologic connection between 2-D layered structures and 3-D diamond structures for conventional semiconductors.

Wang J, Zhang Y - Sci Rep (2016)

Bottom Line: When coming to identify new 2D materials, our intuition would suggest us to look from layered instead of 3D materials.Each path is found to further split into two branches under tensile strain-low buckled and high buckled structures, which respectively lead to a low and high buckled monolayer structure.Most promising new layered or planar structures identified include BeO, GaN, and ZnO on the tensile strain side, Ge, Si, and GaP on the compressive strain side.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Computer Engineering, The University of North Carolina at Charlotte 9201 University City Boulevard, Charlotte, NC 28223, USA.

ABSTRACT
When coming to identify new 2D materials, our intuition would suggest us to look from layered instead of 3D materials. However, since graphite can be hypothetically derived from diamond by stretching it along its [111] axis, many 3D materials can also potentially be explored as new candidates for 2D materials. Using a density functional theory, we perform a systematic study over the common Group IV, III-V, and II-VI semiconductors along different deformation paths to reveal new structures that are topologically connected to but distinctly different from the 3D parent structure. Specifically, we explore two major phase transition paths, originating respectively from wurtzite and NiAs structure, by applying compressive and tensile strain along the symmetry axis, and calculating the total energy changes to search for potential metastable states, as well as phonon spectra to examine the structural stability. Each path is found to further split into two branches under tensile strain-low buckled and high buckled structures, which respectively lead to a low and high buckled monolayer structure. Most promising new layered or planar structures identified include BeO, GaN, and ZnO on the tensile strain side, Ge, Si, and GaP on the compressive strain side.

No MeSH data available.


Related in: MedlinePlus

Phase transition curves for silicon with either wurtzite or NiAs structure (including high and low bucking), and planar structures with AA and AB stacking.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4835777&req=5

f5: Phase transition curves for silicon with either wurtzite or NiAs structure (including high and low bucking), and planar structures with AA and AB stacking.

Mentions: Shown in Fig. 5 are the phase transition curves under compression and expansion starting from either WZ or NiAs phase for Si. In addition, two curves for planar AA and AB structures are also included. One significant feature is that under tensile strain, for either the WZ or NiAs curve, the transformation curve actually splits into two branches: one corresponding to the LB structure that has been shown, respectively, in Figs 2 and 4; the other branch, which was not shown there, corresponding to a HB structure that has not been identified before. After the splitting point, the HB branch in fact has lower energy. For the WZ curve, the HB structure has a total energy minimum at c = 4.8 Å, and the curve in fact extrapolates to the HB monolayer structure reported previously6. For the NiAs curve, the HB minimum occurs at c = 4.4 Å. Unfortunately, neither of these minima yields a metastable state, based on the appearance of imaginary phonon modes. At c → ∞, the two LB branches merge to the same point – silicene, which is structurally stable6, although not necessary chemically stable (i.e., easily reacting with other species). Similarly, at c → ∞, the two HB curves merge together, but none of them is structurally stable. The curve for the AB stacking planar structure is found to have a minimum at c = 5.2 Å, which actually corresponds to the “graphitic” Si reported earlier13. Again, this is not a metastable state from the phonon calculation, but nevertheless might be possible to achieve if constrained by a proper substrate. The energy minimum of planar structure with AB stacking is higher than that of planar structure with AA stacking, which is similar to the case that the energy of the NiAs phase is higher than the WZ phase. However, there is an energy barrier between them.


Topologic connection between 2-D layered structures and 3-D diamond structures for conventional semiconductors.

Wang J, Zhang Y - Sci Rep (2016)

Phase transition curves for silicon with either wurtzite or NiAs structure (including high and low bucking), and planar structures with AA and AB stacking.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835777&req=5

f5: Phase transition curves for silicon with either wurtzite or NiAs structure (including high and low bucking), and planar structures with AA and AB stacking.
Mentions: Shown in Fig. 5 are the phase transition curves under compression and expansion starting from either WZ or NiAs phase for Si. In addition, two curves for planar AA and AB structures are also included. One significant feature is that under tensile strain, for either the WZ or NiAs curve, the transformation curve actually splits into two branches: one corresponding to the LB structure that has been shown, respectively, in Figs 2 and 4; the other branch, which was not shown there, corresponding to a HB structure that has not been identified before. After the splitting point, the HB branch in fact has lower energy. For the WZ curve, the HB structure has a total energy minimum at c = 4.8 Å, and the curve in fact extrapolates to the HB monolayer structure reported previously6. For the NiAs curve, the HB minimum occurs at c = 4.4 Å. Unfortunately, neither of these minima yields a metastable state, based on the appearance of imaginary phonon modes. At c → ∞, the two LB branches merge to the same point – silicene, which is structurally stable6, although not necessary chemically stable (i.e., easily reacting with other species). Similarly, at c → ∞, the two HB curves merge together, but none of them is structurally stable. The curve for the AB stacking planar structure is found to have a minimum at c = 5.2 Å, which actually corresponds to the “graphitic” Si reported earlier13. Again, this is not a metastable state from the phonon calculation, but nevertheless might be possible to achieve if constrained by a proper substrate. The energy minimum of planar structure with AB stacking is higher than that of planar structure with AA stacking, which is similar to the case that the energy of the NiAs phase is higher than the WZ phase. However, there is an energy barrier between them.

Bottom Line: When coming to identify new 2D materials, our intuition would suggest us to look from layered instead of 3D materials.Each path is found to further split into two branches under tensile strain-low buckled and high buckled structures, which respectively lead to a low and high buckled monolayer structure.Most promising new layered or planar structures identified include BeO, GaN, and ZnO on the tensile strain side, Ge, Si, and GaP on the compressive strain side.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical and Computer Engineering, The University of North Carolina at Charlotte 9201 University City Boulevard, Charlotte, NC 28223, USA.

ABSTRACT
When coming to identify new 2D materials, our intuition would suggest us to look from layered instead of 3D materials. However, since graphite can be hypothetically derived from diamond by stretching it along its [111] axis, many 3D materials can also potentially be explored as new candidates for 2D materials. Using a density functional theory, we perform a systematic study over the common Group IV, III-V, and II-VI semiconductors along different deformation paths to reveal new structures that are topologically connected to but distinctly different from the 3D parent structure. Specifically, we explore two major phase transition paths, originating respectively from wurtzite and NiAs structure, by applying compressive and tensile strain along the symmetry axis, and calculating the total energy changes to search for potential metastable states, as well as phonon spectra to examine the structural stability. Each path is found to further split into two branches under tensile strain-low buckled and high buckled structures, which respectively lead to a low and high buckled monolayer structure. Most promising new layered or planar structures identified include BeO, GaN, and ZnO on the tensile strain side, Ge, Si, and GaP on the compressive strain side.

No MeSH data available.


Related in: MedlinePlus