AI 中文总结
本研究结合多种表征技术，利用光学耦合低频电噪声谱探究单层MoS2场效应晶体管的硫空位钝化，实现了缺陷浓度降低、器件性能提升，证实该技术可灵敏量化TMDC器件的缺陷钝化效果。
AI 中文摘要
过渡金属二硫化物（TMDC）单层是电子和光子应用的极具前景的材料，但化学气相沉积生长的薄膜性能受本征硫空位的严重限制，这些硫空位会引入带隙中间陷阱态、降低载流子迁移率并升高电噪声。本研究结合X射线光电子能谱、光致发光、拉曼散射与电输运及光学耦合低频噪声谱，探究辛烷硫醇对单层MoS2场效应晶体管中硫空位的钝化作用。硫醇处理将硫空位浓度从7.5%降至5%，使沟道电阻升高35倍，同时恢复了开/关比为10^4的栅极开关特性，并将场效应迁移率从1 cm^2/Vs提升至5 cm^2/Vs。低频噪声谱直接量化了缺陷抑制效果：钝化后霍格参数下降超过两个数量级。与仅靠栅极偏置测量无法获得的机制区别不同，依赖栅极的噪声确认载流子迁移率波动是暗噪声的主导机制，而光激发驱动噪声转变为以载流子数量波动为主，反映了光生载流子通过产生-复合陷阱与残余空位态的优先相互作用。密度泛函理论计算证实了这些发现，显示空位诱导的带隙中间态被抑制超过50%，并部分恢复了本征带隙。这些结果确立了光学耦合低频噪声谱作为一种灵敏、低成本且非破坏性的工具，可用于量化基于TMDC的器件中的缺陷钝化。
英文摘要
Transition metal dichalcogenide monolayers are promising materials for electronic and photonic applications, yet the performance of chemical vapour deposition grown films is severely limited by native sulphur vacancies that introduce mid-gap trap states, degrade carrier mobility, and elevate electrical noise. Here we investigate octane thiol passivation of sulphur vacancies in monolayer MoS2 field effect transistors, combining x-ray photoelectron spectroscopy, photoluminescence, and Raman scattering with electrical transport and optically coupled low-frequency noise spectroscopy. Thiol treatment reduces the sulphur vacancy concentration from 7.5% to 5%, which increases the channel resistance 35-fold while restoring gate switching with an on/off ratio of 10^4 and improving field-effect mobility from 1 to 5 cm^2/Vs. Low frequency noise spectroscopy directly quantifies the defect suppression: the Hooge parameter drops by more than two orders of magnitude after passivation. Gate-dependent noise confirms carrier mobility fluctuation as the dominant dark noise mechanism, while optical excitation drives a crossover to carrier number fluctuation dominated noise, reflecting preferential interaction of photogenerated carriers with residual vacancy states via generation-recombination trapping, a mechanistic distinction inaccessible to gate- bias measurements alone. Density functional theory calculations corroborate these findings, showing suppression of vacancy-induced mid-gap states by more than 50% and partial restoration of the intrinsic bandgap. These results establish optically coupled low-frequency noise spectroscopy as a sensitive, low-cost, and non-destructive tool for quantifying defect passivation in TMDC-based devices.
