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Deep ultraviolet monitoring is realized via a high crystal quality SnO2 microwire (MW)‐based photodetector (PD). This is then combined with 2D nitrogen‐doped graphene (NGr), conducting polymer polypyrrole (PPy), and an in situ polymerization‐fabricated composite film PPy‐NGr to construct an organic–inorganic p–n heterojunction PD. The long response time brought on by the oxygen adsorption of SnO2 MW is greatly decreased via coating with the aforementioned materials. A defect response is created by the surface dangling bonds of SnO2 MW, which can be effectively suppressed by the PPy. Absorption in the deep ultraviolet region (<240 nm) by PPy results in a blue shift of the response peak of the PPy/SnO2 heterojunction PD compared to that of a single SnO2 PD. The introduction of NGr improves the detection performance by providing a smoother energy band migration to reduce photogenerated carrier recombination and stacking at the potential barrier. The ultrahigh responsivity of PPy‐NGr/SnO2 PD is 4594.25 A W−1 and the detectivity is 6.47 × 1011 Jones, 40 and nine times greater, respectively, than those of a PPy/SnO2 PD under a 5 V reverse bias and 240‐nm light irradiation (18.75 µW cm−2). The novel strategy provides a reference for the future design of high‐performance heterojunction PDs.

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This work reports a high‐detectivity solar‐blind deep ultraviolet photodetector with a fast response speed, based on a nitrogen‐doped graphene/βGa2O3/GaN p‐i‐n heterojunction. The i layer of βGa2O3 with a Fermi level lower than the central level of the forbidden band of 0.2 eV is obtained by reversed substitution growth with oxygen replacing nitrogen in the GaN matrix, indicating the majority carrier is hole. X‐ray diffractometershows that the transformation of GaN into βGa2O3 with (−201) preferred orientation at temperature above 900 °C in an oxygen ambient. The heterojunction shows enhanced self‐powered solar blind detection ability with a response time of 3.2 µs (rise)/0.02 ms (delay) and a detectivity exceeding 1012 Jones. Under a reverse bias of −5 V, the photoresponsivity is 8.3 A W−1 with a high Ilight/Idark ratio of over 106 and a detectivity of ≈9 × 1014 Jones. The excellent performance of the device is attributed to 1) the continuous conduction band without a potential energy barrier, 2) the larger built‐in potential in the heterojunction because of the downward shift of Fermi energy level in β‐Ga2O3, and 3) an enhanced built‐in electric field in the βGa2O3 due to introducing p‐type graphene with a high hole concentration of up to ≈1020 cm−3.