Enhancing photodetection efficiency in MoTe2/MoS2 van der Waals heterojunctions by modulating the phase regions

MoTe₂ is a promising candidate for phase change engineering applications due to its low energy barrier between the 2H and 1T' phases. This article presents a method to achieve uniform and patternable phase transitions in MoTe₂ through photolithography and mild plasma treatment. The transition from the 2H phase to the 1T' phase results in excellent uniformity and low roughness. By controlling phase transitions in different regions, the impact on the optoelectronic performance of MoTe₂/MoS₂ heterojunctions is systematically investigated. Devices with phase transitions in the electrode region show the fastest response speed, reaching 40 μs/35 μs. Devices with phase transitions across the full region show superior responsivity, reaching 22.3 mA/W. Selectively applying uniform phase transitions in different regions can effectively modulate the optoelectronic performance of MoTe₂/MoS₂ heterojunctions, offering new possibilities for diverse applications of two-dimensional materials through phase change engineering