###### Abstract  
All-inorganic perovskites, with their low-cost, simple processes and superior heat stability, have become potential candidate materials for photodetectors (PDs). However, they have no representative responsivity in the deep-ultraviolet (UV) wavelength region. As a new-generation semiconductor, gallium oxide (Ga\({}_{2}\)O\({}_{3}\)), which has an ultrawide bandgap, is appropriate for solar-blind (200 nm-280 nm) deep-UV detection. In this work, ultrawide-bandgap Ga\({}_{2}\)O\({}_{3}\) was introduced into an inorganic perovskite device with a structure of sapphire/\(\beta\)-Ga\({}_{2}\)O\({}_{3}\)/Indium Zinc Oxide (IZO)/CsPbBr\({}_{3}\). The performance of this perovskite PD was obviously enhanced in the deep UV region. A low-cost, vacuum-free Mist-CVD was used to realize the epitaxial growth of \(\beta\)-Ga\({}_{2}\)O\({}_{3}\) film on sapphire. By introducing the Ga\({}_{2}\)O\({}_{3}\) layer, the light current of this heterojunction PD was obviously enhanced from 10\({}^{-8}\) to 10\({}^{-7}\), which leds its detectivity (D\({}^{\prime}\)) to reach 1.04 \(\times\) 10\({}^{12}\) Jones under a 254 nm light illumination with an intensity of 500 \(\mu\)W/cm\({}^{2}\) at a 5 V bias. perovskite; Ga\({}_{2}\)O\({}_{3}\); heterojunction photodetector; Mist-CVD; UV responsivity +
Footnote †: journal: Applied Sciences  
an effective blocking layer. This led the devices it was used in to achieve power conversion efficiencies (PCEs) of 21.56%. Furthermore, we used Ga\({}_{2}\)O\({}_{3}\) as an interlayer in PDs that greatly suppressed carrier recombination at interfaces. These PDs, which had structures of FTO/TiO\({}_{2}\)/Ga\({}_{2}\)O\({}_{3}\)/CsPbIBr\({}_{2}\)/Carbon, achieved a detectivity (D*) as high as 1.83 \(\times\) 10\({}^{12}\) [PERSON] [16]. Some reports also revealed the high performance of PDs by combining inorganic wide-bandgap semiconductors and perovskites. For example, [PERSON]'s work used a Au/CH\({}_{3}\)NH\({}_{3}\)PbI\({}_{3}\)/\(\beta\)-Ga\({}_{2}\)O\({}_{3}\)/Ti/Au hybrid structure. This structure's photo-to-dark current ratio was 1460, and its responsivity (R) and D* were 85 mA/W and 1.28 \(\times\) 10\({}^{11}\) [PERSON] [17], respectively. [PERSON]'s work showed lead-free perovskite PDs with heterojunction structures of CsCu\({}_{2}\)I\({}_{3}\)/\(\beta\)-Ga\({}_{2}\)O\({}_{3}\)[18]. The \(\beta\)-Ga\({}_{2}\)O\({}_{3}\) film was prepared with MOCVD, and the optimized devices reached a D* of 10\({}^{7}\) [PERSON]. [PERSON] et al. used MOCVD to heteroepitaxially grow the \(\beta\)-Ga\({}_{2}\)O\({}_{3}\) film and then combined it with CuBiI\({}_{4}\) to achieve a self-powered heterojunction PD [19]. [PERSON]'s work prepared the \(\beta\)-Ga\({}_{2}\)O\({}_{3}\) film using a molecular beam epitaxy (MBE) technique, resulting in metal-semiconductor-metal perovskite PDs with structures of \(\beta\)-Ga\({}_{2}\)O\({}_{3}\)/Au/MAPbBr\({}_{3}\)[20]. In addition to single-crystal Ga\({}_{2}\)O\({}_{3}\) films, many researchers also used Ga\({}_{2}\)O\({}_{3}\) nanowires and amorphous Ga\({}_{2}\)O\({}_{3}\) to prepare Ga\({}_{2}\)O\({}_{3}\) and perovskite hybrid devices. [PERSON]'s work used a vertical structure of \(\beta\)-Ga\({}_{2}\)O\({}_{3}\) nanowires/CH\({}_{3}\)NH\({}_{3}\)PbI\({}_{3}\) heterostructures and exhibited a D* of 5.23 \(\times\) 10\({}^{11}\) [PERSON] under self-powered conditions [21]. [PERSON]'s work reported a device with a structure of FTO/\(\alpha\)-Ga\({}_{2}\)O\({}_{3}\) nanowires/MAPbBr\({}_{3}\)/Ag and a D* of 1.21 \(\times\) 10\({}^{12}\) [PERSON] [22]. [PERSON]'s work also reported the radio-frequency magnetron sputtering of the prepared amorphous Ga\({}_{2}\)O\({}_{3}\) film. Devices with structures of FTO/Ga\({}_{2}\)O\({}_{3}\) (amorphous)/MAPbCl\({}_{3}\)/spiro-OMeTAD/Ag had a D* of 5.4 \(\times\) 10\({}^{10}\) [PERSON] [23]. However, most of the above reports prepared their Ga\({}_{2}\)O\({}_{3}\) film using conventional methods such as PLD, MOCVD, or MBE, which have high costs and require a vacuum environment.