Geometric structures and electronic properties of the Bi2X2Y (X, Y = O, S, Se, and Te) ternary compound family: a systematic DFT study. Issue 48 (28th November 2018)

• Record Type: Journal Article
• Authors: Ma, Xiaoyu; Chang, Dahu; Zhao, Chunxiang; Li, Rui; Huang, Xiaoyu; Zeng, Zaiping; Huang, Xiaowei; Jia, Yu
• Is Part Of: Journal of materials chemistry. Volume 6:Issue 48(2018)
• Page Start: 13241
• Page End: 13249
• Publication Date: 2018-11-28
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c8tc04587a
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : The geometric structure and electronic properties of Bi2 X2 Y (X, Y = O, S, Se, and Te) ternary compound have been studied by means of first-principles density functional theory. Abstract : Bi2 X3 (X = S, Se, and Te) binary compounds have been widely studied as thermoelectric materials and reference topological insulators. Replacing one of the X atoms with a different atom Y of the same group has resulted in a new family of ternary compounds Bi2 X2 Y (X, Y = O, S, Se, and Te), which have attracted increasing attention very recently. By means of first-principles calculations within density functional theory, we have systematically studied the geometric structures and electronic properties of the whole family of these ternary compounds. We find that these compounds can be divided into two major groups. The first is traditional semiconductors, which include (i) Bi2 O2 Y, (ii) Bi2 S2 Y, and (iii) Bi2 OY2 . The other is topological insulators, which are (i) Bi2 Se2 Y and (ii) Bi2 Te2 Y. The optimized lattice parameters, band gaps as well as effective masses are in excellent agreement with recently available experimental measurements. In particular, we have found a new semiconductor material Bi2 S2 Te, which possesses an orthorhombic structure in space group pnma with a moderate direct gap of 0.5 eV at the HSE06 level and a small hole effective mass (∼0.22 m 0 ), which should favour fast hole transport and deserves further experimental studies. This work provides a road map for the exploration of the fundamental properties of the ternary compounds in this family as well as for their practical applications at the device level.