Effects of molecular adsorption on carrier transport properties of large-size graphene

The temperature dependent resistance and thermoelectric power of macroscopic graphenes are studied in various gas environments. The temperature dependent slope of resistance is weaker in gas environments with heavier molecules. Following the temperature dependent slopes of normalized resistance, one can identify the molecular mass of the environmental gas. This is relative to the atomically sharp potential modification due to adsorbed gas molecules on the graphene. The temperature dependent thermopower increases as the mass of the gas molecules increases. A universal relationship between resistance and thermoelectric power in various gas environments further confirms that the transport mechanism is dominated by the adsorbed gas molecules on the graphene surface