Plasmonic Photovoltaic Effect of an Original 2D Electron Gas System and Application in Mid‐Infrared Imaging

Owing to their consistently emerging applications in modern photonics, highly sensitive and rapid mid‐infrared (MIR) photodetectors, operating at high temperatures, are of great significance. Herein, a novel PbTe/Ge heterostructure is introduced. Notably, the discovery of a 2D electron gas (2DEG) system on the surface of the PbTe layer is experimentally identified for the first time. A high‐performance PbTe/Ge heterostructure MIR photodetector utilizing a plasmonic photovoltaic effect is developed by employing asymmetric electrodes. The photodetecting device demonstrates an exceptionally high detectivity of 1.1 × 1011 Jones along with a short response time of 15 ns at room temperature. Additionally, the proposed plasmonic photovoltaic mechanism of the device is investigated and mainly ascribed to the propagating plasmons, generated by the coupling of the 2DEG with incident MIR photons. Moreover, a linear detector array (LDA) of PbTe/Ge is demonstrated for a thermal imaging application, which exhibits promising high‐quality real‐time imaging via the 2D photodetector arrays on Ge‐based integrated circuits. This work opens up a new way for the development of next‐generation, advanced MIR photonic devices and integrated photonic systems. A 2D electron gas system (2DEG) in the newly synthesized PbTe/Ge heterostructure is discovered. A plasmonic photovoltaic MIR photodetector is developed using the 2DEG characteristics, operating at high temperatures with high detectivity and fast response speed. Thermal imaging application of the plasmonic photovoltaic MIR photodetector is demonstrated by further developing PbTe/Ge 2DEG linear detector array.