Ultrafast reversible photoconductivity in 2D MoTe/Pt van der Waals heterostructure.

Two-dimensional (2D) materials, particularly transition metal dichalcogenides, have exceptional optoelectronic properties, making them highly promising for next-generation photonic integrated circuits. Despite great advancements in 2D optoelectronic devices, achieving ultrafast and controllable photoconductivity polarity inversion with a single device remains a fundamental challenge due to the static nature of built-in electric fields at metal/2D material interfaces. This study demonstrates a transient electric field reversal at the MoTe/Pt Schottky junction, enabling photoconductivity inversion from negative to positive within 100 ps. By applying ultrafast photocurrent detection, a minimal voltage variation (10 mV) precisely controls this transition, and a device with a remarkable photocurrent response time of 3.8 ps is proposed. This work advances the design of ultrafast, tunable photodetectors, offering potential applications in high-speed optical communication, ultrafast imaging, and quantum information processing.