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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 path around NiAs-like structure.The line with red squares indicates the total energy vs. layer separation and the line with blue circles indicates the buckling height vs. layer separation.
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f4: Phase transition path around NiAs-like structure.The line with red squares indicates the total energy vs. layer separation and the line with blue circles indicates the buckling height vs. layer separation.

Mentions: For a given compound XY, among the three possible AB stacked structures: (1) AXB, (2) AYB stacking, and (3) . tends to be more energetically favorable over AXB or AYB. For instance, for GaN and BN, both and AXB are shown to be stable but AYB is unstable from the phonon calculations, agreeing with previous findings for GaN21 and h-BN181920. The total energy based phase transition path for the structure has been explored in Fig. 2, now we investigate the similar phase transition path as well as the variation in buckling parameter for the AXB structure for the same 9 materials with the results shown in Fig. 4. The obtained structure parameters are summarized in Table 2, with comparison to the available literature values. They can be divided into three groups: (i) C and BN with only one total energy minimum, corresponding to the common graphite and one of the known h-BN phases (Δ = 0). (ii) BeO, ZnO, and GaN with two total energy minima that correspond to the NiAs (Δ ≠ 0) and planar phase (Δ = 0), respectively. For BeO and GaN, the NiAs phase has a higher total energy than the planar, whereas for ZnO, the NiAs phase is lower. (iii) Si, Ge, GaP, and ZnTe with only one total energy minimum, corresponding to the NiAs phase. The NiAs phase has previously been studied for GaN14, ZnO15, and ZnTe16, but the structural stability has not been explicitly examined. In contrast to a previous report suggesting the existence of BN in NiAs phase35, we do not find NiAs phase for BN. We have performed phonon calculations for the NiAs phase and planar phase, and found that: (1) the NiAs phase is stable for Si, Ge, GaN, GaP, and ZnO, but not for BeO; (2) the AXB planar phase (p-AXB) is stable for C and BN, as is known; however, for GaN, ZnO, and BeO, even though there is a secondary total energy minimum point, the AXB planar structure is unstable, judging by the existence of imaginary phonon modes. (3) Nevertheless, BeO in stacking, p-, is a stable planar phase, which has not been reported before, as shown as an inset of the BeO panel in Fig. 4; and (4) some imagine modes were found for the NiAs phase ZnTe. In short, NiAs phase is only stable for binaries with moderate size atoms; p-AXB is only stable for binaries with small size atoms; neither NiAs nor p-AXB is stable for BeO, but is.


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

Wang J, Zhang Y - Sci Rep (2016)

Phase transition path around NiAs-like structure.The line with red squares indicates the total energy vs. layer separation and the line with blue circles indicates the buckling height vs. layer separation.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Phase transition path around NiAs-like structure.The line with red squares indicates the total energy vs. layer separation and the line with blue circles indicates the buckling height vs. layer separation.
Mentions: For a given compound XY, among the three possible AB stacked structures: (1) AXB, (2) AYB stacking, and (3) . tends to be more energetically favorable over AXB or AYB. For instance, for GaN and BN, both and AXB are shown to be stable but AYB is unstable from the phonon calculations, agreeing with previous findings for GaN21 and h-BN181920. The total energy based phase transition path for the structure has been explored in Fig. 2, now we investigate the similar phase transition path as well as the variation in buckling parameter for the AXB structure for the same 9 materials with the results shown in Fig. 4. The obtained structure parameters are summarized in Table 2, with comparison to the available literature values. They can be divided into three groups: (i) C and BN with only one total energy minimum, corresponding to the common graphite and one of the known h-BN phases (Δ = 0). (ii) BeO, ZnO, and GaN with two total energy minima that correspond to the NiAs (Δ ≠ 0) and planar phase (Δ = 0), respectively. For BeO and GaN, the NiAs phase has a higher total energy than the planar, whereas for ZnO, the NiAs phase is lower. (iii) Si, Ge, GaP, and ZnTe with only one total energy minimum, corresponding to the NiAs phase. The NiAs phase has previously been studied for GaN14, ZnO15, and ZnTe16, but the structural stability has not been explicitly examined. In contrast to a previous report suggesting the existence of BN in NiAs phase35, we do not find NiAs phase for BN. We have performed phonon calculations for the NiAs phase and planar phase, and found that: (1) the NiAs phase is stable for Si, Ge, GaN, GaP, and ZnO, but not for BeO; (2) the AXB planar phase (p-AXB) is stable for C and BN, as is known; however, for GaN, ZnO, and BeO, even though there is a secondary total energy minimum point, the AXB planar structure is unstable, judging by the existence of imaginary phonon modes. (3) Nevertheless, BeO in stacking, p-, is a stable planar phase, which has not been reported before, as shown as an inset of the BeO panel in Fig. 4; and (4) some imagine modes were found for the NiAs phase ZnTe. In short, NiAs phase is only stable for binaries with moderate size atoms; p-AXB is only stable for binaries with small size atoms; neither NiAs nor p-AXB is stable for BeO, but is.

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