Open Access

Fig. 1

image

Download original image

Schematic of the ultrafast I-V measurement. (a) Oscillating THz probe with controllable peak field ETHz incident from free space, induces the time-dependent current in graphene j = σETHz, which leads to the attenuation of the THz probe field ΔE THz due to the conductivity of graphene σ. The Fourier transforms of the THz probes measured before and after the interaction with graphene yield its frequency-dependent conductivity. Thus, the conductivity of graphene is determined for all the frequencies contained in the single-cycle THz probe, the amplitude spectrum (b) of which is covering the operation frequency range of both current and next-generation MOSFETs. The experiment in (a) is repeated for several values of the THz peak field strength in the range 2.3-120 kV/cm, yielding the ultrafast and contact-free I-V characterization of graphene – its frequency- and peak field- dependent conductivity spectrum.