Configurable microcavity-enhanced graphene photothermoelectric terahertz detectors

Abstract

Terahertz (THz) detectors with high sensitivity, fast response speed, room temperature operation, and self-powered feature are the key component for many THz applications. Microcavity resonators can effectively improve the sensitivity of THz detectors. However, it is difficult to precisely evaluate the microcavity resonator induced such improvement in experiment. Here, we realize a configurable microcavity–antenna-integrated graphene photothermoelectric (PTE) THz detector. Through the microcavity–antenna hybrid structure, THz radiations are localized and enhanced at one end of the graphene channel, and the temperature difference along the channel is greatly increased, resulting in the strong enhancement of PTE response. At the resonant frequency, the device has a high responsivity (976 V/W), low noise equivalent power (2.87 pW / Hz 1/2 ), and fast response speed (300 ns) at room temperature and in zero-bias operation mode. The microcavity-induced peak enhancement factor of 13.14 is accurately extracted. The microcavity–antenna introduced enhancement is further confirmed by using a two-temperature heat transfer model. The strategy of using a configurable microcavity is useful for further optimizing THz detectors by introducing the critical coupling mechanism.