Optoelectronic Characterization of 2D Graphene‐Based Heterostructures: Gr/MoS2 and Gr/WS2

Abstract

In this research, it is aimed to obtain and to compare the electrical conductivity and the transmittance of two graphene (Gr)‐based heterostructures: Gr/WS2 and Gr/MoS2 on quartz. Raman spectroscopy is used to analyze the quality of the samples before and after the measurements. Terahertz time domain spectroscopy in transmission mode is used as a nondestructive technique to obtain the surface conductivity and the transmittance in the frequency range [0.2, 1.6] THz. The transmittance values obtained for both samples are similar, whereas the surface conductivity of Gr/WS2 is higher than the one of Gr/MoS2 and both are higher than the conductivity values obtained for individual homogeneous layers. Fourier transform infrared spectroscopy and UV–Vis spectroscopies are used to obtain the optical transmittance and to evaluate the behavior of each layer in the frequency ranges [90, 180] and [300, 1200] THz, respectively. In the infrared range, the transmittance of the heterostructures is similar to that of the individual materials, although in the visible range the transmittance is totally dominated by the WS2 and MoS2 layers. These characteristics make these heterostructures good candidates to be used for optoelectronics sensors.