Universal ac conduction in large area atomic layers of CVD-grown MoS 2

Here, we report on the ac conductivity [σ′(ω) ;10mHz<ω<0.1MHz] measurements performed on atomically thin, two-dimensional layers of MoS2 grown by chemical vapor deposition (CVD). σ′(ω) is observed to display a "universal" power law, i.e., σ′(ω)∼ωs 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.