Electronic, Elastic and Piezoelectric Properties of Two-Dimensional Group-IV Buckled Monolayers* *Supported by the National Natural Science Foundation of China under Grant No 51672208, the National Science and Technology Pillar Program during the Twelfth Five-Year Plan Period under Grant No 2012BAD47B02, the Sci-Tech Research and Development Program of Shaanxi Province under Grant Nos 2010K01-120, 2011JM6010 and 2015JM5183, the Shaanxi Provincial Department

Abstract

Electronic, elastic and piezoelectric properties of two-dimensional (2D) group-IV buckled monolayers (GeSi, SnSi and SnGe) are studied by first principle calculations. According to our calculations, SnSi and SnGe are good 2D piezoelectric materials with large piezoelectric coefficients. The values of d 11 of SnSi and SnGe are 5.04 pm/V and 5.42 pm/V, respectively, which are much larger than 2D MoS2 (3.6 pm/V) and are comparable with some frequently used bulk materials (e.g., wurtzite AlN 5.1 pm/V). Charge transfer is calculated by the Löwdin analysis and we find that the piezoelectric coefficients (d 11 and d31) are highly dependent on the polarizabilities of the anions and cations in group-IV monolayers.