Linear and elliptical photogalvanic effects in two-dimensional penta-BP₅ photodetector

As a typical penta two-dimensional material and proposed to be potentially synthesized, in this paper we built a two-probe photodetector based on the penta-BP₅ monolayer, and further studied linear and elliptical photogalvanic effects in this device. It was found that produced photocurrents in the BP₅ photodetectors mainly show sine relation on double times of the polarized or elliptical angle for the incident light, and the relation can be modulated by the photon energy and polarized angle. Interestingly, due to high asymmetry of the BP₅ monolayer, the pristine BP₅ photodetector generates very high photocurrents, which are even larger than those including vacancy- and substitution-doping, and this result further proved that asymmetry plays a decisive role in the generation of robust photogalvanic effects, instead of introducing impurities to enhance this effect. Furthermore, the linear photogalvanic effect is stronger than the elliptical photogalvanic effect, and the BP₅ photodetectors for the pristine, vacancy- and substitution-doping cases have relatively high extinction ratios showing these BP₅ photodetectors are all polarization-sensitive. In conclude, these results manifest great potential applications of the penta-BP₅ photodetectors on high performance optoelectronics and nanoelectronic devices.