Top-gated black phosphorus phototransistor for sensitive broadband detection

Abstract

The present work reports on a graphene-like material that is promising for photodetection applications due to its high optical absorption and layer-dependent properties. To date, only narrowband photodetectors have been realized; therefore, extending the working wavelength is becoming more imperative for applications such as high-contrast imaging and remote sensing. In this work, we developed a novel detection technique that provides enhanced performance across the infrared and terahertz bands by using an antenna-assisted top-gated black phosphorus phototransistor. By using the proposed sophisticated design, the adverse effect due to the back-gate that is generally employed for a long-wavelength photon coupling can be eliminated. Moreover, the antenna-assisted near-field and dark current can be further tailored electromagnetically and electrostatically by employing a gate finger, thus resulting in improved detection efficiency. Various detection mechanisms such as thermoelectric, bolometric, and electron–hole generation are differentiated on the basis of the device geometry and incident wavelength. The proposed photodetector demonstrated superior performance—excellent sensitivity of more than 10 V W⁻¹, a noise equivalent power value of less than 0.1 nW Hz^−0.5, and a fast response time across disparate wavebands. Thus, the photodetector can satisfy diverse application requirements.