Growth of highly uniform 2-inch MoS₂ wafers using liquid precursor spraying

With the progress of study, MoS₂ has been proven to show excellent properties in electronics and optoelectronics, which promotes the fabrication of future novel integrated circuits and photodetectors. However, highly uniform wafer-scale growth is still in its early stage, especially regarding how to control the precursor and its distribution. Herein, we propose a new method, spraying the Mo precursor, which is proven to fabricate highly uniform 2-inch monolayer MoS₂ wafers. The Mo-precursor concentration and spray time are the key parameters, which have been systematically studied. The monolayer and bilayer coverage, Raman vibration, and PL emission properties are investigated. It was found that when the Mo-precursor concentration is 10 mg mL^-1 and spray time is 8 min, the as-grown MoS₂ wafer has the highest quality and electrical performance. By studying the electrical properties of transistor arrays, it was found that the MoS₂ transistors show slight vibration, the average ON/OFF ratio is 1.21 × 10⁶, and the maximum carrier mobility is 13.39 cm² V^-1 s^-1 without further optimizing the device fabrication. These results directly indicate that the spray method could fabricate MoS₂ wafers with both high optical and electrical uniformity. Moreover, the influence of bilayer coverage on the optical and electrical properties is studied, which demonstrates that additional bilayer nucleation would increase the scattering centers and thus suppress the electrical performance. By this method, we have successfully grown more than 100 2-inch wafers with a stable process, which further proves its potential application in future MoS₂ electronics and integrated circuits.