The Dirac point or minimum conductivity point was located around 35 V as seen in Figure 4b. GHz frequency response measurements were taken up to 40 GHz at zero back-gate voltage using an improved experimental setup. Structural changes are highlighted selleck products in the discussion later on. The device is supported by a back-gate voltage platform and connected to the 40-GHz signal generator and power sensor through a combination of Cu/Au wires after passing

through subminiature type K (SMK) connectors. Figure 4 Characteristics for a GR-FET GHz detector. (a) Basic two-terminal metal contact. (b) Gate voltage dependence for a bilayer GR-FET at room temperature with observable Dirac point. Results and discussion Based on our previous discussion of the microwave transport properties in GR-FET devices [5], the possibility to utilize GR for THz detection has become a more practical goal. Following the previously discussed approach, a clear response to THz radiation has been observed using the setup shown in Figure 2. The fluctuations in the response of the device can be explained by considering the influence of bolometric and Daporinad purchase nonlinearity effects within the GR material. Exposure to THz radiation will inevitably induce these effects depending on the nature of the sample, whether it is monolayer with semimetallic behavior or bilayer with semiconductor

behavior, resulting in a change in the resistance. Referring back to the original resistance’s room temperature dependence in Figure 3, the outcome of Figure 2 can be understood to be the result of a strong bolometric response that increases the resistance in the metallic-type devices and decreases the resistance in the semiconductor-type devices. In addition, nonlinearity effects play an important role in influencing the response of semiconductor-type devices to THz radiation. Nonlinear response occurs because the band gap excitation energy matches the incident wave frequency. Transitions find more between THz ON and OFF exposure states change the resistance values in a manner that can

be explained by bolometric and nonlinearity effects for both monolayer and bilayer devices. The flat regions of the curves within the first four cycles for sample 3 and Sinomenine the first three cycles for sample 2 show the transitions in the responses between the expected bolometric response and occasionally the nonlinear response. After a short period of time, the response is completely dominated by bolometric effects. To clarify the real bolometric impact, the blue background is subtracted to show the absolute resistance change. Fluctuation amplitude can be clearly seen in Figure 5[10, 11]. The observed results show a clear distinction between the response of single- and bilayer devices in sensing THz radiation. Figure 5 Resistance fluctuation and amplitude response for THz irradiation.