Electrons and phonons in single layers of hexagonal indium chalcogenides from ab initio calculations
Electrons and phonons in single layers of hexagonal indium chalcogenides from ab initio calculations
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DOI：
10.1103/physrevb.89.205416
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发表时间：
2014-03
影响因子：
3.7
通讯作者：
V. Zólyomi;N. Drummond;V. Fal’ko
中科院分区：
文献类型：
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作者：
V. Zólyomi;N. Drummond;V. Fal’ko
我们用密度泛函理论计算了二维In_2X_2晶体的电子能带结构、结合能、声子色散和光学吸收光谱，其中X是S、Se或Te。我们确定了六方In2X2单层膜的两个晶相(α和β)，并表明它们具有不同的喇曼活性声子模式。我们发现这些材料是间接带隙半导体，价带边附近空穴呈宽边状弥散。对于空穴浓度分别为n(S)=6.86×10(13)cm(-2)，n(Se)=6.20×10(13)cm(-2)和n(Te)=2.86×10(13)cm(-2)，对于α-In2X2和n(S)=8.32×10(13)cm(-2)，后一特征导致了Lifshitz相变(空穴掺杂In2X2的费米面拓扑的变化)。β-In2X2的n(Se)=6.00×10(13)cm(-2)，n(Te)=8.14×10(13)cm(-2)。
We use density functional theory to calculate the electronic band structures, cohesive energies, phonon dispersions, and optical absorption spectra of two-dimensional In2X2 crystals, where X is S, Se, or Te. We identify two crystalline phases (alpha and beta) of monolayers of hexagonal In2X2, and show that they are characterized by different sets of Raman-active phonon modes. We find that these materials are indirect-band-gap semiconductors with a sombrero-shaped dispersion of holes near the valence-band edge. The latter feature results in a Lifshitz transition (a change in the Fermi-surface topology of hole-doped In2X2) at hole concentrations n(S) = 6.86 x 10(13) cm(-2), n(Se) = 6.20 x 10(13) cm(-2), and n(Te) = 2.86 x 10(13) cm(-2) for X= S, Se, and Te, respectively, for alpha-In2X2 and n(S) = 8.32 x 10(13) cm(-2), n(Se) = 6.00 x 10(13) cm(-2), and n(Te) = 8.14 x 10(13) cm(-2) for beta-In2X2.