Universal ac conduction in large area atomic layers of CVD-grown MoS2

Here, we report on the ac conductivity [sigma'(omega); 10 mHz < omega < 0.1 MHz] measurements performed on atomically thin, two-dimensional layers of MoS2 grown by chemical vapor deposition (CVD). sigma'(omega) is observed to display a universal power law, i.e., sigma'(omega) similar to omega(s) measured within a broad range of temperatures, 10 K < T < 340 K. The temperature dependence of s indicates that the dominant ac transport conduction mechanism in CVD-grown MoS2 is due to electron hopping through a quantum mechanical tunneling process. The ac conductivity also displays scaling behavior, which leads to the collapse of the ac conductivity curves obtained at various temperatures into a single master curve. These findings establish a basis for our understanding of the transport mechanism in atomically thin, CVD-grown MoS2 layers.