Effect of O₂ Plasma Treatment on the Thickness Uniformity of Chemical Vapor Deposited MoS₂ Thin Films on SiO₂ Substrates

Molybdenum disulfide (MoS₂) is extensively investigated as a key element of next-generation thin-film transistors with high carrier mobility and low power consumption. However, for practical application, uniform growth of MoS₂ must be developed on large-area substrates, especially on SiO₂ substrates. Therefore, we investigated the effect of O₂ plasma treatment of SiO₂/p⁺⁺-Si substrates to enhance the thickness uniformity of chemical-vapor-deposited (CVD) MoS₂ thin films. Raman and atomic force microscopy measurements showed that O₂ plasma treatment of SiO₂ substrates improved the thickness uniformity of CVD MoS₂ thin films. Based on the higher surface reactivity after O₂ plasma treatment suggested by contact angle measurement and X-ray photoelectron spectroscopy analysis, we attribute the enhanced thickness uniformity to the uniform nucleation of CVD MoS₂ thin films. These results demonstrate the effectiveness of using O₂ plasma treatment in improving the thickness uniformity of CVD MoS₂ thin films on SiO₂ substrates, with potentially important implications of growing other two-dimensional semiconductor thin films.