Thickness-induced structural phase transformation of layered gallium telluride

Q. Zhao; T. Wang; Y. Miao; F. Ma; Y. Xie; X. Ma; Y. Gu; J. Li; J. He; B. Chen; S. Xi; L. Xu; H. Zhen; Z. Yin; J. Li; J. Ren; W. Jie

doi:10.1039/C6CP01963C

Thickness-induced structural phase transformation of layered gallium telluride†

Q. Zhao,^a T. Wang,*^a Y. Miao,^b F. Ma,*^b Y. Xie,^c X. Ma,*^c Y. Gu,^a J. Li,^a J. He,^a B. Chen,^a S. Xi,^a L. Xu,^a H. Zhen,^a Z. Yin,^a J. Li,^a J. Ren^a and W. Jie^a

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* Corresponding authors

^a State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an, P. R. China
E-mail: taowang@nwpu.edu.cn

^b State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, P. R. China
E-mail: mafei@mail.xjtu.edu.cn

^c State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology, School of Advanced Materials and Nanotechnology, Xidian University, Xi'an, P. R. China
E-mail: xhma@xidian.edu.cn

Abstract

The thickness-dependent electronic states and physical properties of two-dimensional materials suggest great potential applications in electronic and optoelectronic devices. However, the enhanced surface effect in ultra-thin materials might significantly influence the structural stability, as well as the device reliability. Here, we report a spontaneous phase transformation of gallium telluride (GaTe) that occurred when the bulk was exfoliated to a few layers. Transmission electron microscopy (TEM) results indicate a structural variation from a monoclinic to a hexagonal structure. Raman spectra suggest a critical thickness for the structural transformation. First-principle calculations and thermodynamic analysis show that the surface energy and the interlayer interaction compete to dominate structural stability in the thinning process. A two-stage transformation process from monoclinic (m) to tetragonal (T) and then from tetragonal to hexagonal (h) is proposed to understand the phase transformation. The results demonstrate the crucial role of interlayer interactions in the structural stability, which provides a phase engineering strategy for device applications.

Physical Chemistry Chemical Physics

Thickness-induced structural phase transformation of layered gallium telluride†

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