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Self-powered photodetectors have paved the way for electronic applications in fields such as civilian communication, infrared mapping, and industrial automatic control. However, most self-powered photodetectors have faced photoresponse-speed and device-scale bottlenecks. Herein, a novel, selfpowered detector with an ultrafast response speed based on a core-shell InN/In 2 S 3 nanorod array is proposed. A wafer-scale InN/In 2 S 3 nanorod array with good homogeneity is synthesized on Si substrates via a simple two-step method involving molecular beam epitaxy and chemical vapor deposition. The photodetector device exhibits excellent self-powered properties and a high current on/off ratio of 5 × 10 3 . Further analyses determined that the device have an excellent photovoltaic responsivity and detectivity of 140 mA•W −1 and 4.0 × 10 10 Jones, respectively (0 V). Impressively, the device exhibits an ultrafast photoresponse with a rise/fall time of 22/32 µs. The self-powered InN/ In 2 S 3 photodetector with an ultrafast response speed shows superior potential for electronic applications. The core-shell nanostructure hybrid heterojunction introduces a novel idea for wafer-scale nano-photodetectors.

Photodetectors In article number 2201193, Wenliang Wang, Guoqiang Li, and co‐workers present high‐performance photodetectors based on an axial InN/InGaN nanorod arrays heterojunction. The unique chargetransport pathways along the axial heterojunction and the band alignment of the heterojunction significantly improve the response speed of the photodetector. The devices hold great potential in optoelectronic information technology.

requires the photodetection wavelength of the photo detector could match the source wavelength. [4][5][6] In this regard, the bandgap tunable semiconductor and its fabricated photodetector with fast response speed have become a research hotspot. [7][8][9] InGaN semiconductors can achieve wavelength-selective absorption owning to their tunable bandgap (0.65-3.4 eV), which is adjusted by varying the composition of Indium (In). [10][11][12] Thanks to the development of semiconductor industry technology, the InGaN photodetector with PIN and integrated structure has been used in visible light communication systems. [13][14][15] However, the above InGaN-based ultrafast photodetector heavily relies on expensive, slow, complex material growth and chip preparation processes. [16] Accordingly, the development of a simple-structured photodetector with a fast response speed is urgently needed. [17] The photodetector with simple heterojunction demonstrates fast photodetection owing to the built-in electric field to facilitate carrier separation and transport. [18,19] Among the III-nitrides materials, on account of the high electron mobility (4400 cm 2 V −1 s −1 ), the InN semiconductors are widely used to fabricate fast photodetectors. [20,21] Regarding the mentioned above, the InN/InGaN heterojunction is considered a promising candidate for preparing a fast photodetector. This is well known that the high-performance photodetector composed of wide band gap materials lies on top of the narrow band gap materials, thus the InGaN should be grown on the top of InN. [22] However, this InN/InGaN heterojunction cannot be realized due to the growth temperature of InGaN is higher than the dissociation temperature of InN.The dilemma above might be solved by introducing 1D InN nanorod array (NRA) to InGaN films, which could not only relax the strain to form defect-free lattice-mismatched heterostructures but also break through the material arrangement limit of the bandgap. [23,24] Previous research has reported an InN/InGaN heterojunction with the structure of InN NRA on the InGaN epilayer and applied it to optoelectronic devices. [25,26] Nevertheless, this method needs phase-separated from In-rich InGaN buffer as the nucleation sites, which will cause the diameter uniformity of these structures to be poor. The axial heterojunction structure is an effective strategy, on one hand, the diameter uniformity of InN could be controlled, on the other hand, the 1D geometry could confine carriers separation in a very small NRA Due to wavelength-selective characteristics, the InGaN-based photodetectors show bright prospects in visible light communication and fast imaging system. However, the application of InGaN photodetectors with simple structures is limited in the above field owing to the slow response speed. Herein, an ultrafast photodetector based on axial InN/InGaN nanorod array (NRA) heterojunction is prepared through a self-catalytic high (930 °C) and low (400 °C) temperature two-step growth method by molecular beam epitaxy (MBE). The perf...