Hot Electron Engineering in Layered Heterojunctions for Efficient Infrared Detection

Although infrared detection is of high technological and strategic importance, the narrow-bandgap materials used for infrared detection often suffer from poor air stability and pose environmental hazards. Hot electron-based detectors avoid such issues by using conventional wide bandgap semiconductors and exploiting intraband transition. However, hot electron infrared detectors usually suffer from poor quantum efficiency. By photoexciting MoS₂ conduction electrons over a thin barrier layer, here we show that a reversal of the role of the emitter and collector results in a >1000-fold enhancement in the photoresponse compared with a conventional metal/2D semiconductor Schottky diode. We reveal that electron-electron scattering plays a key role in the device performance, which can be effectively tuned by a gate voltage. The photodetector exhibits a nearly flat response up to a measurement wavelength of 1800 nm with a responsivity of 42 mA/W (@1550 nm) at room temperature. We demonstrate an operating frequency of 30 kHz @1550 nm excitation (100 kHz @633 nm). The detector chip is integrated with post-processing electronics in a printed circuit board, making it readily useable for system-level applications─a demonstration of heterogeneous integration of 2D materials with conventional electronics.