High‐Performance HfS 2 ‐HfO X ‐WSe 2 P‐i‐N Photodetector Based on Self‐Oxidized HfS 2

ABSTRACT 2D transition metal dichalcogenides (TMDs) have attracted considerable interest for next‐generation optoelectronics owing to their layer‐tunable bandgap and strong light‐matter interaction. Indeed, 2D TMDs‐based photodetectors are facing an intrinsic trade‐off between responsivity and response speed, as well as the unexpectedly large dark current. Particularly, customizing P‐i‐N structures through incorporating an insulating interlayer between p‐type and n‐type semiconductors simultaneously suppresses dark current and enables faster response. Nevertheless, preparing insulating layer typically requires complex epitaxial growth techniques that exhibit poor compatibility with 2D TMDs materials. Although the P‐i‐N structure also can be achieved more readily by dry‐ or wet‐transfer, yet leaving contaminants and defects at the interface. Here, we report an innovative strategy for realizing high‐performance HfS 2 ‐HfO X ‐WSe 2 P‐i‐N photodetectors through controlled self‐limiting surface oxidation to form an insulating interlayer HfO X . The introduction of HfO X effectively reduces dark current through the high potential barrier, while transfers the carrier transport mechanism to tunneling. Consequently, the HfS 2 ‐HfO X ‐WSe 2 photodetector exhibits markedly enhanced performance, with the light switching ratio increasing from 22 to 10 5 and the responsivity rising from 0.034 A/W to 0.245A/W. Our study offers a novel and exceptionally simple route to 2D P‐i‐N photodetectors that is compatible with 2D semiconductor technology.