Computational Prediction for Stable Structures of Graphene Van Der Waals Heterostructures Composed of Group-III-V Compounds
Authors: Akiyama Toru , Nakamura Kohji , Ito Tomonori 
Published: December 2020

Two-dimensional (2D) materials with honeycomb structure such as graphene have attracted much attention due to their potential applications in nanoelectronics devices. [1] Furthermore, 2D van der Waals (vdW) heterostructures can be formed by stacking different types of 2D layered materials through the weak interlayer vdW interaction, and have attracted interest due to unique functionalities which are impossible in homogeneous bulk materials. [2,3] For instance, various graphene and hexagonal boron nitride (h-BN) related vdW heterostructures have been demonstrated and their physical properties have been discussed. On the other hand, a new class of 2D materials composed of traditional group III–V materials have been recently proposed. Lucking et al. predicted that the double-layer honeycomb (DLHC) structure where pair of single layer honeycomb structure forms interlayer bonds can be realized in various group III-V, II–VI, and I–VII materials, and some of these 2D materials exhibit exotic topological properties. [4] It has also been reported that most of group III–V and II–VI thin films are stabilized by forming the DLHC structure when the thickness deceases toward the 2D limit whereas a structure with alternating octagonal and square rings called a haeckelite structure is favorable beyond 3–15 monolayers depending on the constituent elements. [5] These findings suggest the realization of a new class of vdW heterostructures consisting of conventional 2D materials (such as graphene, h-BN, and transition-metal dichalcogenides) and DLHC structure. In this study, we explore new stable structures of vdW heterostructures composed of group III-V compounds on the basis of density functional calculations taking account of vdW interaction.
The calculations for superlattices consisting of MoS2/AlAs heterostructure reveal that covalent Al-S bonds are formed between Al atoms of AlAs with zinc blende structure and S atoms of MoS2, which stabilizes zinc blende phase over the DLHC structure. This indicates that the combination of transition-metal dichalcogenides and group III-V compounds such as MoS2/AlAs hardly forms vdW heterostructures. On the other hand, we find that vdW heterostructures can be formed for the superlattices consisting of graphene and group III-V compounds (AlAs, AlSb, GaAs, GaSb, InP, InAs, InSb) when its thickness is two monolayers. Furthermore, the vdW heterostructure with DLHC structure in group III-V compounds is more stable than that with conventional zinc blende structure. Therefore, a stable structure whose atomic configurations are different from those of bulk phase is newly found for the combination of graphene and DLHC structure. The calculated biding energies are ranging from 0.22 to 0.30 eV/unit cell, indicating that this vdW heterostructures can be stabilized even at room temperature. The calculations of phonon dispersion also reveal that no imaginary frequencies are present for graphene/InAs with DLHC structure, suggesting its dynamical stability. This is due to nearly coherent in-plane lattice matching (misfit of ~0.1 %) between InAs with DLHC structure and graphene, as demonstrated in InAs nanowire growth by vdW epitaxy. [6] These calculated results suggest that diverse combinations and exotic electronic properties could be discovered in the vdW heterostructures consisting of graphene and group III-V compounds.

Acknowledgements: This work was supported in part by the Grant-in-Aid for Scientific Research Grant (JP20K05324, JP19K05268, and JP16H06418) from the JSPS, and KIOXIA Corporation (former Toshiba Memory Corporation).

References: [1] K. S. Novoselov et al., Science 306, 666 (2004). [2] A. K. Geim and I. V. Grigorieva, Nature 499, 419 (2013). [3] K. S. Novoselov, A. Mishchenko, A. Carvalho, and A. Castro Neto, Science 353, aac9439 (2016). [4] M. C. Lucking, W. Xie, D.-H. Choe, D. West, T.-M. Lu, and S. B. Zhang, Phys. Rev. Lett. 120, 086101 (2018). [5] T. Akiyama, Y. Hasegawa, K. Nakamura, and T. Ito, Appl. Phys. Express 12, 125501 (2019). [6] Y. J. Hong, W. H. Lee, Y. Wu, R. S. Ruoff, and T. Fukui, Nano Lett. 12, 1431 (2012).

Figure 1