Collaborative Innovation Centre of Advanced Microstructures, Nanjing University , Nanjing 210093, People's Republic of China.
Nano Lett. 2017 Jun 14;17(6):3471-3477. doi: 10.1021/acs.nanolett.7b00418. Epub 2017 May 5.
Phase transitions in 2D materials can lead to massive changes in electronic properties that enable novel electronic devices. Tantalum disulfide (TaS), specifically the "1T" phase (1T-TaS), exhibits a phase transition based on the formation of commensurate charge density waves (CCDW) at 180 K. In this work, we investigate the impact of substrate choice on the phase transitions in ultrathin 1T-TaS. Doping and charge transfer from the substrate has little impact on CDW phase transitions. On the contrary, we demonstrated that substrate surface roughness is a primary extrinsic factor in CCDW transition temperature and hysteresis, where higher roughness leads to smaller transition hysteresis. Such roughness can be simulated via surface texturing of SiO/Si substrates, which controllably and reproducibly induces periodic strain in the 1T-TaS and thereby enables the potential for engineering CDW phase transitions.
二维材料中的相变可以导致电子性质的巨大变化，从而实现新型电子设备。二硫化钽（TaS），特别是“1T”相（1T-TaS），在 180K 时通过形成准同型电荷密度波（CCDW）发生相变。在这项工作中，我们研究了衬底选择对超薄 1T-TaS 中相变的影响。掺杂和来自衬底的电荷转移对 CDW 相变的影响很小。相反，我们证明了衬底表面粗糙度是 CCDW 转变温度和滞后的主要外在因素，其中较高的粗糙度导致较小的转变滞后。这种粗糙度可以通过 SiO2/Si 衬底的表面织构来模拟，这种织构可以在 1T-TaS 中可控且可重复地诱导周期性应变，从而为工程化 CDW 相变提供了可能性。
