位移场驱动的少层PtSe2低能输运重建
Displacement-field-driven reconstruction of low energy transport in few-layer PtSe2
中文总结 AI 辅助
该研究针对接近半导体-半金属转变的少层PtSe2，通过实验和Wannier输运计算揭示位移场可重塑其低能电子结构，实现对输运的电学调控，拓展了带隙工程的应用。
中文摘要 AI 辅助
在层状半导体中，垂直位移场会产生层间电势差，该电势差与层间杂化相互竞争，进而改变带隙和承载电流的有限密度电子态。要解析这种相互作用，需要材料接近半导体到半金属的转变，在此中等电场即可强烈重塑低能电子结构。本文研究双栅极半导体PtSe2中位移场驱动的输运，其显著的厚度依赖电子结构使其可进入该低带隙区域。与更薄层不同，六层PtSe2的位移场响应强烈，它处于半导体到半金属转变的边缘，仅具有很小的残余输运带隙。即使微弱的位移场也会在电荷中性附近快速抑制该残余带隙，驱动系统进入带重叠区域。同时，在重空穴掺杂区域电导率降低，表明位移场不仅改变带隙，还改变导电价带态。固定弛豫时间Wannier输运计算重现了这两种响应，显示它们源于场诱导的带重叠以及价带色散的重建。这些结果确立了有限密度输运作为位移场驱动电子结构重建的灵敏探针，并将电学控制扩展到传统带隙工程之外的领域。
英文摘要
In layered semiconductors, a perpendicular displacement field generates an interlayer potential difference that competes with interlayer hybridization, modifying both the band gap and the finite-density electronic states that carry current. Resolving this interplay requires a material lying close to the semiconductor-to-semimetal transition, where moderate electric fields can strongly reshape the low-energy electronic structure. Here, we investigate displacement-field-driven transport in dual-gated semiconducting PtSe2, whose pronounced thickness-dependent electronic structure provides access to this low-band-gap regime. Unlike thinner layers, the displacement-field response is strong in six-layer PtSe2, which lies at the verge of the semiconductor-to-semimetal crossover with only a small residual transport gap. Even weak displacement fields rapidly suppress this residual gap near charge neutrality, driving the system toward a band-overlap regime. At the same time, the conductivity decreases in the heavily hole-doped regime, demonstrating that the displacement field modifies not only the gap but also the conducting valence-band states. Fixed-relaxation-time Wannier transport calculations reproduce both responses, showing that they originate from field-induced band overlap together with reconstruction of the valence-band dispersion. These results establish finite-density transport as a sensitive probe of displacement-field-driven electronic structure reconstruction and extend electrical control beyond conventional band-gap engineering.
