采用化学气相沉积法在氧化硅衬底上合成大面积、高质量的单层MoS2二维材料, 系统表征了材料的光学特性, 并制备出高性能的n型场效应晶体管器件.进一步研究了外加电场对其荧光光谱特性的影响.结果表明：在室温条件下, 单层MoS2的荧光光谱的最强特征峰由A-(带电激子态)、A(本征激子态)两个发光峰构成, 并且二者的特征能量差约为35 meV; 通过调节底栅电压, 测得发光峰随着栅压由负变正表现出明显的峰位红移和强度改变, 且两个子峰的强度随栅压变化表现出相反的变化趋势; 外加电场能够有效改变沟道中的载流子浓度, 进而改变单层MoS2荧光光谱的强度和发光峰形状.为研究二维材料发光特性的物理机制提供了重要依据, 此外这种器件的大规模制备为其应用于光电子学器件与系统提供了可能.

Monolayer molybdenum disulfide (MoS2) with large area and high quality have been grown using Chemical Vapor Deposition (CVD) method. The optical properties of MoS2 was characterized systematically and high performance n-type field-effect transistors were fabricated. The effect of applied electrical field on photoluminescence (PL) spectrum of monolayer MoS2 in the devices was also studied. The results showed that the strongest emission peak of the PL spectrum of monolayer MoS2 consist of two peaks, namely A- peak (Charged Exciton) and A peak (Intrinsic Exciton) at room temperature. The energy difference between the two peaks is about 35 meV. The main PL peak shows obvious redshift and intensity change via tuning the back-gate voltage from negative to positive. We also found that the intensity of these two peaks show opposite dependence on the back-gate voltage with spectrum analysis. These results were analyzed and we concluded that the carrier concentration of monolayer MoS2 can be effectively modulated by applied electrical field, which can further affect the intensity and shape of PL spectrum. These results provide significant basis for the research on the physical mechanism of the optical properties of two-dimensional material. Besides, the large-scale preparation of such devices also make it possible to apply these two dimension materials to optoelectronics devices and systems.