Modeling accumulation capacitance-voltage characteristic of MoS₂ thin flake transistors

We report a theoretical investigation on the accumulation capacitance in MoS₂ thin flake transistors using a two-valley band structure. To obtain the relevant two-valley band structure parameters, first-principles calculations are performed. Then, the capacitance-voltage characteristic in the accumulation layer is simulated by a self-consistent Poisson–Schrödinger solution. It is found that the occupation of the K valley in the conduction band has a significant contribution to the accumulation capacitance, especially in the strong accumulation layer. More importantly, the calculated results using a two-valley band structure is in good agreement with the published experimental data without any fitting parameters, highlighting that the inclusion of both the Q and K conduction band valley is necessary to understand the accumulation capacitance in the strong accumulation region. (paper)