Abstract：
Transition metal dichalcogenides (TMDs) exist in two distinct phases: the thermodynamically stable trigonal prismatic (2H) and the metastable octahedral (1T) phase. Phase engineering has emerged as a potent technique for enhancing the performance of TMDs in optoelectronics applications. Nevertheless, understanding the mechanism of phase transition in TMDs and achieving large-area synthesis of phase-controlled TMDs continue to pose significant challenges. This study presents the synthesis of large-area monolayered 2H-MoS2 and mixed-phase 1T/2H-MoS2 by controlling the growth temperature in the chemical vapor deposition (CVD) method without use of a catalyst. The field-effect transistors (FETs) devices fabricated with 1T/2H-MoS2 mixed-phase show an on/off ratio of 107. Photo response devices fabricated with 1T/2H-MoS2 mixed-phase show ≈55 times enhancement in responsivity (from 0.32 to 17.4 A W-1) and 102 times increase in the detectivity (from 4.1 × 1010 to 2.48 × 1012 cm Hz W-1) compare to 2H-MoS2. Introducing the metallic 1T phase within the 2H phase contributes additional carriers to the material, which prevents the electron-hole recombination and thereby increases the carrier density in the 1T/2H-MoS2 mixed-phase in comparison to 2H-MoS2. This work provides insights into the self-doping effects of 1T phase in 2H MoS2, enabling the tuning of 2D TMDs properties for optoelectronic applications.
摘要：
过渡金属二硫属化合物（TMD）存在两个不同的相：热力学稳定的三角棱柱（2H）和亚稳态的八面体（1T）相。相位工程已成为增强光电应用中TMD性能的有效技术。然而，理解TMD中相变的机制和实现相控TMD的大面积合成继续构成重大挑战。这项研究介绍了通过在不使用催化剂的情况下控制化学气相沉积（CVD）方法中的生长温度来合成大面积单层2H-MoS2和混合相1T/2H-MoS2。用1T/2H-MoS2混合相制造的场效应晶体管（FET）器件的开/关比为107。使用1T/2H-MoS2混合相制造的光响应器件的响应度提高了约55倍（从0.32到17.4AW-1），而检测率提高了102倍（从4.1×1010到2.48×1012cmHzW-1）与2H-MoS2相比。在2H相中引入金属1T相有助于材料的额外载流子，与2H-MoS2相比，这可以防止电子-空穴复合，从而增加1T/2H-MoS2混合相中的载流子密度。这项工作提供了对2HMoS2中1T相的自掺杂效应的见解，从而可以调谐用于光电应用的2DTMD特性。
