Research on graphene thermoelectric terahertz detectors based on multi-electrode structure has made important progress

Graphene terahertz detectors are limited by the low switching ratio and weak saturation characteristics of the materials, making it difficult to obtain a high device response in the terahertz band. Graphene devices based on the principle of thermoelectronics have a wide band absorption capacity, and are expected to break through the strict requirements of the device preparation process based on the traditional mixing principle, which is conducive to the integration of large-area devices.

With the support of the National Key R & D Program, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, State Key Laboratory of Infrared Physics, Lu Wei, Chen Xiaoshuang, Wang Lin, Chen Gang, and collaborators avoided traditional device design ideas and adopted a four-terminal resistance structure To realize the electrode interconnection of different devices (as shown in the figure), the study found that the interconnection between the electrodes produces a device switching performance similar to the transistor. At the same time, the researchers generated the asymmetric photocurrent of the graphene channel through the bias effect between the electrodes. Under the effect of the bias voltage, the device photocurrent showed a linear upward trend, resulting in a photocurrent gain, which corresponds to an order of magnitude increase in the device response. . In addition, studies have shown that the local field at the contact position of graphene and metal can drive non-equilibrium carriers and induce changes in the carrier distribution of the graphene channel. Under the bias field, the device produces a photoconductive effect, and the device response can reach 280V / W, the highest value in current international reports. The research work will provide a new way to realize the core devices of portable imaging systems and human medical terahertz characterization equipment. The research work was published in the NPG Asia Materials magazine on April 18, 2018.

Figure. Four-terminal resistive structure device and its bias field induced polarity inversion photocurrent enhancement phenomenon